Reference:Movements: Difference between revisions

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{{#seo:
{{#seo:
|title=Rolex Movements & Calibers — Cross-Family Reference | BezelBase
|title=Rolex Movements & Calibers — Cross-Family Reference | BezelBase
|description=Cross-family caliber catalogue for vintage and discontinued Rolex. Every movement that powered a pre-2020 Daytona, Submariner, GMT-Master, Explorer, or Oyster Perpetual reference, with deep per-caliber technical and visual detail.
|description=Cross-family caliber catalogue for vintage and discontinued Rolex watches, covering the movements used in pre-2020 Daytona, Submariner, GMT-Master, Explorer, and Oyster Perpetual references.
|keywords=Rolex caliber, Rolex movement, cal 4030, cal 4130, cal 727, Valjoux 72, Zenith El Primero, cal 1570, cal 1575, cal 3035, cal 3135, cal 3185, cal 3186, Oysterquartz 5035, Rolex chronograph caliber, vintage Rolex movement
|keywords=Rolex caliber, Rolex movement, cal 4030, cal 4130, cal 727, Valjoux 72, Zenith El Primero, cal 1570, cal 1575, cal 3035, cal 3135, cal 3185, cal 3186, Oysterquartz 5035, Rolex chronograph caliber, vintage Rolex movement
|type=Article
|type=Article
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== Rolex movements ==
== Rolex movements ==


Every caliber below powered a reference documented on this wiki. Each gets its own entry: specification woven into the history rather than boxed off in a table, the visual and finishing details that let a collector recognize a genuine example, and a photograph where one has been sourced and verified. Fitment is kept to a representative reference or two rather than an exhaustive list — the individual [[Reference:oyster-perpetual|reference]] pages carry the full case-by-case detail.
This page covers calibers used by Rolex families in the wiki, including several numbers with no confirmed fitment. Reference pages document individual applications.


The caliber number is engraved on the movement itself and read with the caseback off; it is separate from the case serial, which is the number that dates the watch on the [[Reference:Serial-numbers|serial-number page]]. Where a movement number and case number diverge sharply, as on the stockpiled Prince calibers, the movement was made well before the case it sits in.
The caliber number is engraved on the movement itself and read with the caseback off; it is separate from the case serial, which is the number that dates the watch on the [[Reference:Serial-numbers|serial-number page]]. Where a movement number and case number diverge sharply, as on the stockpiled Prince calibers, the movement was made well before the case it sits in.


Nearly every mechanical Rolex movement on this page, from the earliest Prince calibers through the modern in-house automatics, was physically manufactured by Aegler in Bienne — Rolex's own supplier and, from 2004, its own subsidiary. Two component technologies recur across dozens of the calibers below and are worth understanding once rather than re-explained each time. Glucydur balances, standard on Rolex automatics from the 1930s onward, are a beryllium-bronze alloy — the name fuses "glucinium" (an old name for beryllium) with "dur" for hard — chosen because the alloy resists magnetism and temperature-driven rate variation far better than the steel balances it replaced. Kif shock protection, from the Vallée de Joux firm founded in 1944, cushions the balance staff pivots against impact with a spring-loaded free-bearing jewel setting; Rolex's "Kif Ultraflex" and "Kif Elastor" are Rolex-specific tunings of the same underlying system, not distinct technologies. Parachrom is Rolex's own invention: a niobium-zirconium-oxygen hairspring alloy the company designed and manufactures in-house, introduced from 2000 and distinguished by its blue oxide coating from around 2005, roughly ten times more resistant to shock and largely immune to magnetic fields and temperature swings compared to the Nivarox alloys it replaced.
Aegler in Bienne made most of the mechanical movements covered here. The firm supplied Rolex as an independent manufacturer before becoming its subsidiary in 2004. Aegler also manufactured calibers based on outside designs, including the Valjoux- and Zenith-based chronographs.
 
Several component technologies recur across the range. Glucydur balances, standard on Rolex automatics from the 1930s onward, use a beryllium-bronze alloy that resists magnetism and temperature-driven rate variation better than the steel balances it replaced. The name combines "glucinium," an old name for beryllium, with "dur," meaning hard. Kif shock protection, made by the Vallée de Joux firm founded in 1944, cushions the balance-staff pivots with a spring-loaded free-bearing jewel setting. Rolex used the Kif system under the names "Kif Ultraflex" and "Kif Elastor." Introduced in 2000, Parachrom is Rolex's niobium-zirconium-oxygen hairspring alloy. A blue oxide coating distinguished it from around 2005; Rolex rates it as about ten times more resistant to shock than the Nivarox alloys it replaced, as well as largely immune to magnetism and temperature changes.
<span id="prince-family"></span>
<span id="prince-family"></span>
== Prince (shaped movements) ==
== Prince (shaped movements) ==


The Prince family runs on Aegler shaped movements, older than every other Rolex caliber on this page. Wilsdorf and Aegler patented the layout in 1927: a "shaped watch movement with a seconds dial" that put the winding barrel at one end of the rectangular movement and the balance at the other. That separation is why Prince movements could carry a larger balance wheel than rival shaped calibers of the period, and a bigger mainspring barrel too — better precision, longer reserve, both from the same design choice.
The Prince family uses Aegler shaped movements, older than every other Rolex caliber on this page. Wilsdorf and Aegler patented the layout in 1927 as a "shaped watch movement with a seconds dial." It placed the winding barrel at one end of the rectangular movement and the balance at the other, leaving room for a larger balance wheel and mainspring barrel than rival shaped calibers of the period. The larger balance improved precision, while the larger barrel extended the power reserve.


Aegler made these movements as a supplier, not a Rolex subsidiary. The firm ran independently out of Bienne until Rolex bought it from the Borer family in April 2004. "Aegler" and "Rebberg" refer to the same company — Aegler is the name, Rebberg the street in Bienne where it stood. Aegler also built movements for Gruen, and the architectural sibling of Cal. 300 shipped in the US as the Techni-Quadron under Gruen's own Cal. 877 designation. That shared supplier explains a documented transplant pattern: a Gruen-stamped movement turns up inside a Rolex Prince case now and then. It also explains a real misattribution in the literature — "Cal. 877" occasionally gets listed as a Prince caliber, when it was never a Rolex number at all.
Aegler remained an independent supplier until Rolex bought the company from the Borer family in April 2004. "Aegler" and "Rebberg" refer to the same firm; Rebberg was the street in Bienne where it stood. Aegler also made movements for Gruen. The architectural sibling of Cal. 300 sold in the United States as the Gruen Techni-Quadron, designated Cal. 877. Gruen-stamped movements sometimes appear in Rolex Prince cases, but Cal. 877 was never a Rolex caliber number.


Movement grading across the family runs Prima &rarr; Extra Prima &rarr; Ultra Prima, rising through jewel count, adjustment positions, and chronometer testing rigour. A "Chronometer" or "Observatory" mark on a Prince dial corresponds to Extra Prima or Ultra Prima grade only — a Prima movement never earns it. Rolex submitted Prince movements to the National Physical Laboratory at Kew for rate certificates independent of the Swiss Bureaux Officiels Suisse de Contrôle; the 1914 Class A Kew certificate Rolex commonly cites as its first official chronometer rating belongs to an earlier ladies' wristwatch movement, predating the Prince family, though the Princes continue that Kew-Teddington testing tradition from 1928 forward.
Prince grades run Prima &rarr; Extra Prima &rarr; Ultra Prima, with higher jewel counts, more adjustment positions, and stricter chronometer testing. Only Extra Prima and Ultra Prima watches carry "Chronometer" or "Observatory" dial marks. Rolex submitted Prince movements to the National Physical Laboratory at Kew for rate certificates independent of the Swiss Bureaux Officiels Suisse de Contrôle. Its often-cited 1914 Class A Kew certificate belongs to an earlier ladies' wristwatch movement, while Prince testing at Kew-Teddington began in 1928.


<span id="cal-300"></span>
<span id="cal-300"></span>
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Cal. 300 is the original Prince movement, 1928 to 1935. Rolex's own factory caliber table lists it under size code "T.S.," the same code shared by Cal. 310 and Cal. 350 below — Christie's calls all three "the same movement base," with parts interchangeable between them and only the balance bridge marking which of the three a given example started as. Grading ran Prima (15 jewels, 6-position) through Extra Prima and Ultra Prima (18 jewels, 6-position, some marked Chronometer); researcher David Boettcher's patent work identifies the three extra jewels precisely — two end-stones on the escape-wheel pivots and one top bearing on the centre wheel. Grade wording moved from the ratchet wheel on early production to the main train bridge later on, itself a rough dating tool. The photographed example, an Extra Prima marked "Observatory 6 Positions," shows the later bridge-stamped convention.
Cal. 300 is the original Prince movement, made from 1928 to 1935. Rolex's factory caliber table places it under the "T.S." size code shared by Cal. 310 and Cal. 350. Christie's describes all three as the same movement base, with interchangeable parts and the balance bridge identifying the original execution. Prima movements have 15 jewels and six-position adjustment; Extra Prima and Ultra Prima versions have 18 jewels, six-position adjustment, and sometimes a Chronometer marking. David Boettcher identifies the additional jewels as two end-stones on the escape-wheel pivots and a top bearing on the centre wheel. Early movements carry the grade wording on the ratchet wheel, while later examples place it on the main train bridge. The photographed Extra Prima, marked "Observatory 6 Positions," shows the later convention.
 
Balance metallurgy changed gradually. Examples from 1928 use a bimetallic balance with a plain Breguet spring; by the mid-to-late 1930s, documented movements have both monometallic and bimetallic balances paired with Elinvar-alloy hairsprings. No exact transition year is established. "Patented Superbalance" on later ratchet wheels and bridges refers to Aegler's Swiss patent CH196706, filed in August 1936 and granted in March 1938. A movement carrying the mark postdates the grant. The recessed timing screws are often said to reduce air resistance, but Boettcher reads the patent as a way to maximize the balance's radius of gyration within the available space.


The balance metallurgy shifted over the run: 1928 examples carry a bimetallic balance with a plain Breguet spring, and by the mid-to-late 1930s Antiquorum lots show both monometallic and bimetallic balances paired with Elinvar-alloy hairsprings — a real transition, but a gradual and overlapping one that the auction record never pins to an exact year. "Patented Superbalance," stamped on later ratchet wheels and bridges, refers to Swiss patent CH196706, filed by Aegler — not Rolex directly — in August 1936 and granted March 1938; a movement so marked postdates that grant. The recessed timing screws are often explained as reducing air resistance, but Boettcher argues the patent's real purpose is maximizing the balance's radius of gyration within a small movement, since a plain-rimmed balance can't grow as large in the same footprint. Cal. 300 carries no shock protection, a systematic absence across roughly fifteen Antiquorum Prince lot descriptions spanning 1989 to 2022 — a catalogue style that names shock-absorbers when they're present — consistent with Incabloc only reaching production in 1938, after the Prince's core design was already set. The winding-stem bridge is Cal. 300's known service fail point: a Prince that sets the time and then immediately disengages points to a broken bridge, not a deeper fault, and aftermarket CNC-machined brass replacement bridges and stems circulate among watchmakers as a routine repair part.
Cal. 300 has no shock protection, consistent with Incabloc reaching production only in 1938, after the core Prince design was established. Its winding-stem bridge is a known service weak point. A movement that sets the time and then disengages may have a broken bridge; watchmakers use aftermarket CNC-machined brass bridges and stems for this repair.


UK auction houses have separately catalogued a cluster of three- and four-digit numbers on 1862, 1490, and 1855 movements — 510, 579, 841, 1004, 1130, and 1439, confirmed against specific Bonhams, Christie's, and Tajan lots below, plus a weaker sighting of 701 and a single-sourced 1759. Whether these track distinct Aegler grading tiers or are simply how UK cataloguers transcribe the grade and jewel count stamped on a given movement is unresolved in the record — continental houses (Antiquorum, Christie's Geneva) describe the same class of movement by grade name and the T.S. size code, never by these numbers. Two further numbers sometimes listed alongside them, Cal. 414 and Cal. 527, do not appear in any auction house, dealer, or catalogue record found for the Rolex Prince and are not documented here. A separate case reference, 971A, is sometimes mistaken for a caliber number in secondary listings — the actual movement inside a 971A case is this same T.S./300-family caliber, per Antiquorum's own 1989 cataloguing of one.
Several UK auction catalogues treat the three- and four-digit numbers found on movements in refs 1862, 1490, and 1855 as calibers. The documented numbers are 510, 579, 841, 1004, 1130, and 1439, with weaker evidence for 701 and a single record of 1759. They are almost certainly movement serials read from the plate. Continental catalogues identify the same movement class by grade and the T.S. size code instead. Cal. 414 and Cal. 527 have no documented connection to the Rolex Prince. The number 971A is a case reference, not a caliber; Antiquorum catalogued a 971A in 1989 with the same T.S./300-family movement.


<span id="cal-300-ts"></span>
<span id="cal-300-ts"></span>
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"T.S." is Rolex's own size-family code for this 16.9 × 32.7mm architecture, printed directly by Christie's as "cal. T.S. Ref. 300" — not, as sometimes assumed, an abbreviation for "Très Soigné"; no source found supports that reading. The Ultra Prima 6-position execution built on this base runs 1932 to 1938: lateral lever escapement, monometallic balance on a micrometer regulator, Breguet overcoil hairspring, rhodium plating. It is documented on the [[Reference:1527|1527 Railway]], where the grade mix inverts the pattern seen on the 1490 — Extra Prima dominates the surviving 1527 population, and an 8-position "Officially Tested in Eight Ways" Ultra Prima example is the outlier at the top of the range, the highest-hammering Prince movement recorded (Mondani 2006, bamboo-bracelet 1931 example, CHF 27,140).
"T.S." is Rolex's size-family code for this 16.9 × 32.7mm architecture, catalogued by Christie's as "cal. T.S. Ref. 300." There is no support for the common expansion "Très Soigné." The six-position Ultra Prima execution ran from 1932 to 1938 with a lateral lever escapement, monometallic balance, micrometer regulator, Breguet overcoil hairspring, and rhodium plating. On the [[Reference:1527|1527 Railway]], Extra Prima movements outnumber Ultra Prima examples, reversing the pattern seen on the 1490. An eight-position Ultra Prima marked "Officially Tested in Eight Ways" is documented on a 1931 bamboo-bracelet example sold by Mondani in 2006.


<span id="cal-310"></span>
<span id="cal-310"></span>
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The centre-seconds member of the T.S. family, built for the wedge-shaped [[Reference:3361|3361 Aerodynamic]] / 3362 / [[Reference:3937|3937]] Prince group. Antiquorum's own Hong Kong 2000 cataloguing of a 3361 gives it directly: "7 1/2′′′, rhodium plated, 18 jewels, lateral lever escapement, Superbalance balance adjusted to 6 positions, self-compensating Breguet balance-spring, micrometer regulator," 19 × 49mm cased. Antiquorum never prints the number "310" itself in that description — the caliber-number attribution to specific serial examples rests on dealer listings rather than the auction house's own text, worth flagging as weaker than the architecture description around it. Production ended in 1938, but Aegler kept stockpiling movements that Rolex cased into 3361 production through 1952; a 1952-cased example with a movement number far lower than its case number is the stockpile pattern showing up directly in the serial record.
Cal. 310 is the centre-seconds member of the T.S. family, used in the wedge-shaped [[Reference:3361|3361 Aerodynamic]], 3362, and [[Reference:3937|3937]] Prince group. Antiquorum described a 3361 in 2000 as a rhodium-plated 7½-ligne movement with 18 jewels, lateral lever escapement, six-position Superbalance, self-compensating Breguet balance spring, and micrometer regulator, in a 19 × 49mm case. That catalogue does not print the number 310, so the caliber attribution is less secure than the architecture and specifications. Movement production ended in 1938, but Aegler stock remained in Rolex cases through 1952. A 1952 example with a movement number far below its case number illustrates this stockpile pattern.


<span id="cal-360-hw"></span>
<span id="cal-360-hw"></span>
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Sources disagree sharply on this caliber, and both readings are printed here rather than picking one. Christie's cataloguing of a 1938 ref. 2835 "Prince Elegant" gives a tonneau-shaped 15-jewel movement, and collector-book author Charles Jarman describes Cal. 360 as "manually wound, small seconds register, tonneau shaped, with a Superbalance" — the reading behind this page's earlier framing of it as a 1936-onward tonneau-plate successor to Cal. 300, used as a visual dating tell on 971, 1490, 1862, and 3361 cases. Against that, a Rolex factory caliber table lists Cal. 360 as rectangle-shaped, 18 × 27mm — a size class well below the 300 family's 16.9 × 32.7mm — 18 jewels, dated 1937, and marked as its own "Basic Caliber" rather than a 300 derivative. The nickname "HW," popularly explained as Hans Wilsdorf's initials, rests on a single dealer source; the same factory table instead shows a size code that reads as "F-LW" in that document, plausibly an OCR artifact of the same "F" size family that also produces Cal. 180's "F." code — the founder-initials story has no independent support and the size-code reading fits the table's own naming pattern better. With the architecture itself disputed, escapement and balance detail aren't asserted here either — a firm reading would mean picking a side in a disagreement the sources themselves haven't settled.
The architecture of Cal. 360 is disputed. Christie's describes a 1938 ref. 2835 "Prince Elegant" with a tonneau-shaped 15-jewel movement, and Charles Jarman's ''The Rolex Reference Guide'' (4th edition) calls Cal. 360 a manual, small-seconds, tonneau-shaped movement with a SuperBalance. Rolex's factory caliber table instead lists a rectangular 18-jewel Basic Caliber measuring 18 × 27mm, smaller than the Cal. 300 family's 16.9 × 32.7mm.
 
Both Jarman and the factory table date its introduction to 1937. The disagreement concerns its shape, size, and relationship to Cal. 300. The popular claim that "HW" means Hans Wilsdorf has no independent support; the factory table appears to give the size code as "F-LW," possibly an OCR rendering related to the "F" size-family code used for Cal. 180. Shigeharu Aritake's ''Rolex Scene 1913–1997'' is cited for a progression in which SuperBalance wording disappears from the winding wheel around 1938, but this does not resolve the architecture. Escapement and balance details remain unconfirmed.


<span id="cal-510"></span>
<span id="cal-510"></span>
=== Cal. 510 ===
<span id="cal-579"></span>
<span id="cal-701"></span>
<span id="cal-841"></span>
<span id="cal-1004"></span>
<span id="cal-1130"></span>
<span id="cal-1439"></span>
=== Numbered Prince movements (510, 579, 701, 841, 1004, 1130, 1439) ===
 
Seven numbers circulate as Prince "calibers": 510, 579, 701, 841, 1004, 1130, and 1439. All are most likely movement serial numbers misread as caliber designations, so they are grouped here.
 
Photographed Prince plates carry a grade legend, jewel count, "Swiss Made," and a bare number stamped beside the "NN RUBIES" wording, but no caliber designation. Grade legends include Prima, Extra Prima, Ultra Prima, Observatory Quality, Officially Tested in Eight Ways, Timed 6 Positions, and For All Climates. The bare number ranges from four to seven digits. Ultra Prima 18-jewel examples with otherwise matching plates carry 1260, 1439, and 1759 in that position, confirming that the stamp varies within one movement type.
 
Continental auction catalogues identify these movements by size code and grade, such as "cal. T.S. 300" or "7½′′′ T.S. 300, Observatory Quality." UK lots that print a "Cal." figure also give a separate case or serial number, indicating that the supposed caliber was read from the movement. The specifications also overlap: 1439 and 1759 both describe an 18-jewel Ultra Prima movement adjusted to six positions. A bare mainplate serial has likewise appeared in print as a "1240 calibre movement."
 
Auction descriptions use these numbers, but the available evidence identifies them as movement serials.
 
{| class="wikitable" style="font-size:90%;"
! number
! documented on
! catalogue text
! notes
|-
| 510
| Prince Brancard ref. 1855, serial 143**, circa 1930
| "17-jewel Cal.510 manual wind movement tested to 8 positions"
| 8-position adjustment, against the more typical 6
|-
| 579
| stainless steel ref. 1862, circa 1935, case No. 103
| "17-jewel Cal.579 manual wind movement" (Bonhams London)
| single lot; the trailing "T" in some listings is absent from Bonhams' catalogue text
|-
| 701
| one photograph showing "ROLEX PRINCE 701" on a 1930s piece
| none
| no recorded jewel count, adjustment count, or technical description; no auction or catalogue attribution
|-
| 841
| ref. 1862 circa 1930, case No. 10403
| "17-jewel Cal.841 manual wind" (Bonhams London; resold through Tajan in 2019, the same watch catalogued twice)
| a separate listing gives 15 jewels for a "Cal. 841T" on a different 1862; a caliber designation would not change jewel count
|-
| 1004
| ref. 1862, Glasgow import mark for 1936, serial 176**
| "17-jewel Cal.1004 manual wind movement tested to 8 positions" (Bonhams, December 2015)
| white gold bezel, fixed wire lugs, gilt brick-link bracelet
|-
| 1130
| 9K yellow gold ref. 1490, case 30280
| "cal. 1130 manual winding lever movement, 16 jewels"
| lowest jewel count recorded in the group
|-
| 1439
| Prince Chronometre ref. 1490, Glasgow import mark for 1937, serial 307**
| "18-jewel Cal.1439 manual wind movement timed to 6 positions" (Bonhams)
| same 18-jewel, 6-position Ultra Prima specification as Cal. 1759 below
|}
 
Cal. 1759 is the same phenomenon. It remains separate because the photographed watch preserves matching movement and caseback markings, but the number appears in the serial position on an Ultra Prima plate and is documented in only one regional UK auction.
 
<span id="cal-1759"></span>
=== Cal. 1759 ===
[[File:Cal 1759 movement.webp|thumb|right|220px|Cal. 1759, "1759, 18 RUBIES, ULTRA PRIMA," with its matching case back]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
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|-
|-
| jewels
| jewels
| 17
| 18
|}
|}


Documented on the Prince Brancard ref. 1855, catalogued as a "17-jewel Cal.510 manual wind movement tested to 8 positions" — the same unusual 8-position adjustment seen on Cal. 1004 below, against the more typical 6-position Prima/Extra Prima/Ultra Prima standard.
This circa 1937 Ultra Prima Chronometer has 18 jewels and six-position adjustment. Gardiner Houlgate catalogued it in a 9ct ref. 1862 with 1937 Glasgow import hallmarks as a "cal. 1759 Ultra Prima Chronometer 18 jewel movement timed 6 positions." The photographed example retains its matching caseback, engraved "1759, 18 Rubies, Ultra Prima" alongside "31 Records Universels" and a retailer stamp. The identification rests on this single regional UK auction lot.


<span id="cal-579"></span>
<span id="cal-350-ts"></span>
=== Cal. 579 ===
=== Cal. 350 T.S. ===
[[File:Cal 350 TS movement.webp|thumb|right|220px|Cal. 350 T.S., Extra Prima grade, 15 rubies, timed to 6 positions, in a ref. 1491 jumping hour]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
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|-
|-
| jewels
| jewels
| 17
| 15 or 18 (documented both ways)
|-
| size
| 16.9 &times; 32.7mm (T.S.)
|-
| escapement
| Lateral lever
|-
| balance
| Monometallic
|}
|}


Bonhams London catalogued a stainless steel ref. 1862, circa 1935, case No. 103, directly as a "17-jewel Cal.579 manual wind movement" — single-sourced to that one lot. Earlier listings of this number carried a trailing "T," which does not appear in Bonhams' own description; the letter is an aggregator-database artifact rather than Rolex or Aegler terminology, and is dropped here.
Cal. 350 is the jump-hour member of the T.S. family, alongside the small-seconds Cal. 300 and centre-seconds Cal. 310. Christie's and Sotheby's catalogue it in the [[Reference:1491|1491 Brancard Jumping Hour]] as an 18-jewel, chronometer-rated movement on the T.S. base. Another 1491 has a 15-jewel Extra Prima movement; Ultra Prima examples have 18 jewels. Jewel count varies with grade. The jump-hour disc works on much the same principle as the later Datejust date disc. Surviving examples carry Glasgow import hallmarks from 1930–31, consistent with the T.S. base's 1928–35 production window.
 
The 1491 case is deeper than the 1490 to accommodate the jump-hour module. Case depth distinguishes a genuine 1491 from a 1490 fitted with a later module. Known service faults include a weak jump-impulse spring that causes a "lazy" disc advance, a worn retention pawl that makes the hour disc jitter, and a misaligned dial aperture that exposes parts of two numerals.


<span id="cal-701"></span>
<span id="bubbleback-family"></span>
=== Cal. 701 ===
== Bubbleback and early automatic ==
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! value
|-
| type
| Manual
|}


The weakest of the numbers on this page: a UK dealer's photograph shows "ROLEX PRINCE 701" legible on a 1930s piece, but no accompanying jewel count, adjustment count, or any other technical description has surfaced anywhere. The marking is real; nothing beyond it is currently documented.
Bubbleback and early Oyster Perpetual references use a distinct family of self-winding calibers. They followed the Prince's manual shaped movements and preceded the standardized post-war automatic line. The "bubble" refers to the domed caseback needed to clear the full-rotor automatic mechanism. It was not a bumper system, although many competing automatics still used one.


<span id="cal-841"></span>
<span id="cal-520"></span>
=== Cal. 841 ===
=== Cal. 520 ===
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
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|-
|-
| type
| type
| Manual
| Automatic
|-
|-
| jewels
| jewels
| 17 (Bonhams) / 15 (one auction listing)
| 19
|}
|-
 
| frequency
Bonhams London, ref. 1862 circa 1930, case No. 10403: "17-jewel Cal.841 manual wind." The same number resold through Tajan in 2019 as "17-jewel Cal.841 manual wind" on the identical watch — one example catalogued twice, not two independent sightings. A separate, smaller consignor listing gives 15 jewels for a "Cal. 841T" on a different 1862, a contradiction worth keeping rather than resolving. As with Cal. 579, the trailing "T" seen in some listings traces to an aggregator database field, not the original auction-house text.
| 18,000 vph (2.5 Hz)
 
<span id="cal-1004"></span>
=== Cal. 1004 ===
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! value
|-
|-
| type
| escapement
| Manual
| Straight-line lever
|-
|-
| jewels
| balance
| 17
| Superbalance
|}
|}


Bonhams London, 18K two-colour gold bracelet ref. 1862, Glasgow import mark 1936: "17-jewel Cal.1004 manual wind movement tested to 8 positions" — the same 8-position outlier seen on Cal. 510, against the usual 6-position standard.
Cal. 520 debuted in the original 1933 ref. 1858 with its three-piece Oyster case. Antiquorum describes the 8¾-ligne rhodium-plated movement in a [[Reference:3353|3353]] as automatic, with 19 jewels, 18,000 vph, a straight-line lever escapement, and a Superbalance with Breguet balance spring. Cal. 620 superseded it as the architecture developed through the mid-1930s. No confirmed movement photograph is available; a generic early Bubbleback movement should not be identified as a 520 unless the engraved caliber number is visible.


<span id="cal-1130"></span>
<span id="cal-620"></span>
=== Cal. 1130 ===
=== Cal. 620 ===
[[File:Cal 620 movement.webp|thumb|right|220px|Cal. 620, EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
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|-
|-
| type
| type
| Manual
| Automatic
|-
|-
| jewels
| jewels
| 16
| 17
|}
 
Documented on a 9K yellow gold ref. 1490, case 30280, catalogued as a "cal. 1130 manual winding lever movement, 16 jewels" — the lowest jewel count recorded for a numbered Prince movement on this page.
 
<span id="cal-1439"></span>
=== Cal. 1439 ===
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! value
|-
|-
| type
| frequency
| Manual
| 18,000 vph (2.5 Hz)
|-
|-
| jewels
| power reserve
| 18
| 35h
|}
|-
 
| size
Bonhams, Prince Chronometre ref. 1490, Glasgow import mark 1937: "18-jewel Cal.1439 manual wind movement timed to 6 positions" — back to the standard 6-position count after the 510/1004 outliers.
| 11½ lignes / 26.4mm × 7.5mm
 
<span id="cal-1759"></span>
=== Cal. 1759 ===
[[File:Cal 1759 movement.webp|thumb|right|220px|Cal. 1759, "1759, 18 RUBIES, ULTRA PRIMA," with its matching case back]]
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! value
|-
|-
| type
| escapement
| Manual
| Straight-line lever
|-
|-
| jewels
| balance
| 18
| Superbalance (monometallic)
|}
|}


The Ultra Prima Chronometer execution, circa 1937: 18 jewels, 6-position adjustment, documented at Gardiner Houlgate on a 9ct ref. 1862 with Glasgow import hallmarks for 1937, catalogued directly as "cal. 1759 Ultra Prima Chronometer 18 jewel movement timed 6 positions." The photographed example pairs the movement with its original case back, engraved "1759, 18 Rubies, Ultra Prima" alongside "31 Records Universels" and the retailer stamp — a rare survival of movement and original case together. Gardiner Houlgate is a regional UK specialist house rather than one of the major auction rooms, and this number is currently single-sourced to that one lot.
Derived from the manual Cal. 600, Cal. 620 became the base for Rolex's early full-rotor automatic family. Antiquorum catalogues individual examples with 17 to 20 jewels, against the table's 17-jewel specification. Earlier 1940s movements have a swan-neck micrometer regulator without shock protection; by the early 1950s, an index regulator and shock absorber appear.
 
Its defining feature is a unidirectional "Perpetual" rotor that turns through 360 degrees without bumpers or buffers. The rotor is engraved "ROLEX PERPETUAL / CHRONOMETER / SWISS MADE / PATENTED / SUPER-BALANCE," while the three-screw, 18mm cover plate reads "VIS TIRETTE / PATENTED / TRIGGER SCREW." Cal. 620 powered the original 1931 "Perpetual" and early Bubblebacks. Cal. 630 and the related 635 and 645 developed from the same architecture.


<span id="cal-350-ts"></span>
<span id="cal-630"></span>
=== Cal. 350 T.S. ===
=== Cal. 630 ===
[[File:Cal 630 movement.webp|thumb|right|220px|Cal. 630, EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 282: Line 337:
|-
|-
| type
| type
| Manual
| Automatic
|-
|-
| jewels
| jewels
| 18
| 17
|-
| frequency
| 18,000 vph (2.5 Hz)
|-
|-
| size
| size
| 16.9 &times; 32.7mm (T.S.)
| 26.0mm
|-
|-
| escapement
| escapement
| Lateral lever
| Straight-line lever
|-
|-
| balance
| balance
Line 297: Line 355:
|}
|}


The jump-hour member of the T.S. family, alongside Cal. 300 (small seconds) and Cal. 310 (centre seconds) above. Christie's Geneva (14 May 2018, lot 113) and Sotheby's Geneva (November 2016, lot 135) both catalogue it in the [[Reference:1491|1491 Brancard Jumping Hour]]: an 18-jewel, chronometer-rated movement on the T.S. base, in the 1491's rectangular case. Watch Wiki notes the jump-hour disc mechanism works on much the same principle the Datejust's date disc would decades later — an early instance of a mechanism Rolex returned to on a completely different watch. Surviving examples carry Glasgow import hallmarks from 1930-31, consistent with the shared T.S. base's own 1928-35 production window.
Launched in 1937, Cal. 630 was chronometer-certified under the period Swiss testing system, adjusted to seven positions, and fitted with a Breguet hairspring. One secondary source gives 18 jewels rather than the table's 17. The movement developed directly from Cal. 620 and shares its "Vis Tirette *** Patented *** Trigger Screw" cover-plate marking. Its rotor and bridge also carry the same "Rolex Perpetual Chronometer, Swiss Made, Patented, Super-Balance" signature. The caliber number stamped in the small box on the bridge distinguishes the two.


Two further notes apply across the whole family rather than to one caliber. The 1491 case runs deeper than the 1490's to house the jump-hour module — that case-depth difference is the canonical way to catch a 1490 retrofitted with a later module and passed off as a genuine 1491. Three module-specific service patterns turn up in the collector record: a weak jump-impulse spring producing a "lazy" disc advance, a worn disc-retention pawl producing hour-disc jitter, and a misaligned dial aperture that reveals fragments of two numerals at once.
<span id="cal-105-hunter"></span>
 
=== Cal. 10½ Hunter ===
<span id="bubbleback-family"></span>
[[File:Cal 700 movement.webp|thumb|right|220px|Cal. 700, the 10½-ligne Hunter, monometallic Superbalance, shown in its Oyster case]]
== Bubbleback and early automatic ==
 
Bubbleback and early Oyster Perpetual references run on a distinct family of early self-winding calibers, separate from the Prince's manual shaped movements and predating the standardized post-war automatic line. The "bubble" in Bubbleback describes the domed caseback these movements needed to clear their automatic rotor — a genuine self-winding mechanism, not a bumper system, at a time when most competing automatics still used one.
 
<span id="cal-520"></span>
=== Cal. 520 ===
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 313: Line 365:
|-
|-
| type
| type
| Automatic
| Manual
|-
|-
| jewels
| jewels
| 19
| 17–18
|-
|-
| frequency
| frequency
| 18,000 vph (2.5 Hz)
| 18,000 vph (2.5 Hz)
|-
| size
| 10½ lignes
|-
|-
| escapement
| escapement
Line 325: Line 380:
|-
|-
| balance
| balance
| Superbalance
| Superbalance, 6-position
|-
| regulator
| Swan-neck micrometer
|}
|}


The first Bubbleback caliber, debuting in the original 1933 reference 1858 with its three-piece Oyster case: automatic, 19 jewels, 18,000 vph, straight-line lever escapement, Superbalance with a Breguet balance spring, per Antiquorum's own cataloguing of a 3353 example (8¾′′′ rhodium-plated). Documented on the [[Reference:3353|3353]] by case description. Superseded by Cal. 620 as the movement architecture matured through the mid-1930s. No individually-confirmed movement photograph has surfaced for this caliber yet — treat any generic "early Bubbleback movement" image with a 520 label with caution unless the caliber number is visible engraved on the piece.
This Aegler-supplied 10½-ligne hand-wound family uses the 700/710 architecture. It has a straight-line lever escapement, monometallic Superbalance adjusted to six positions, self-compensating Breguet balance spring, and swan-neck micrometer regulator, with no documented shock protection. The movement powers the original Air-King 4925 and its Air-Lion, Air-Tiger, and Air-Giant siblings, including the sub-seconds 4365, mid-size 4444, and 4647 Hunter Precision. Its architecture links the pre-war Prince and Bubbleback movements with the post-war automatic Cal. 1030. Rolex's factory caliber table dates Cal. 700 and 710 to 1938. It lists Cal. 720 separately as an automatic movement with shock protection, not as a third member of this manual pair.


<span id="cal-620"></span>
<span id="cal-600"></span>
=== Cal. 620 ===
=== Cal. 600 ===
[[File:Cal 620 movement.webp|thumb|right|220px|Cal. 620, EmmyWatch]]
[[File:Cal 600 movement.webp|thumb|right|220px|Cal. 600, manual, Super Balance — EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
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Line 338: Line 396:
|-
|-
| type
| type
| Automatic
| Manual
|-
|-
| jewels
| jewels
Line 344: Line 402:
|-
|-
| frequency
| frequency
| 18,000 vph (2.5 Hz)
| Not recorded
|-
|-
| power reserve
| power reserve
| 35h
| Not recorded
|-
|-
| size
| size
| 11½ lignes / 26.4mm × 7.5mm
| 9&frac34; lignes / 21.7mm
|-
|-
| escapement
| escapement
| Straight-line lever
| Not recorded &mdash; Cal. 620 derivative is straight-line lever
|-
|-
| balance
| balance
| Superbalance (monometallic)
| Patented Super Balance
|-
| regulator
| Not recorded &mdash; Cal. 620 derivative is micrometer, later index
|-
| shock
| None documented
|}
|}


11½ lignes, 26.4mm diameter, 7.5mm height, 17 jewels (Antiquorum lots range 17-20 across individual examples), 18,000 vph, 35 hours of reserve, derived from the manual-wind Cal. 600. Straight-line lever escapement, monometallic Superbalance, Breguet balance spring — the regulator changes across the run, a swan-neck micrometer regulator and no shock protection on earlier 1940s examples, an index regulator with a shock absorber added by the early 1950s. The rotor is the defining feature: a uni-directional "Perpetual" weight that spins a full 360 degrees with no bumpers or buffers, at a time when competing automatics still relied on bumper systems. It's engraved "ROLEX PERPETUAL / CHRONOMETER / SWISS MADE / PATENTED / SUPER-BALANCE," and an 18mm cover plate held by three screws carries its own "VIS TIRETTE / PATENTED / TRIGGER SCREW" marking. Cal. 620 powered the original 1931 "Perpetual" and the early Bubbleback generation, and is the base architecture Cal. 630 (and the related 635, 645) evolved from directly.
Cal. 600 sits one size class below the 10&frac12;-ligne 700/710/720 family and carries a patented Super Balance. Sotheby's catalogued the movement in the Mercedes Gleitze Oyster in November 2025 as a rhodium-finished Hunter-architecture base upgraded to Cal. 600. The late-1926 27mm case belongs to the watch Gleitze wore during her 21 October 1927 Channel swim attempt and is engraved "Miss M. Gleitze / The Companion 'Oyster.' Vindication Channel Swim. October 21st. 1927."
 
Rolex's factory table lists Cal. 600 as a Basic Caliber: manual wind, small seconds, 21.7mm, 17 jewels, entered in 1933 under a Hunter-patent size bracket. It is the root of the 9&frac34;-ligne automatic branch. Cal. 620 followed in 1936, with Cal. 635, 640, and 645 descending from that line in 1950. Both the factory table and Sotheby's Gleitze catalogue give 17 jewels.
 
The Gleitze case carries Glasgow import marks for 1926/1927, but its movement is later. Rolex's factory table dates Cal. 600 to 1933, and the stamped Super Balance refers to Aegler's Swiss patent CH196706, filed in August 1936 and granted in March 1938. The movement is a service replacement fitted at least a decade after the 1927 swim. A mid-1970s Rolex service box accompanied the watch. The case and engraving establish the watch's historical provenance; the present movement is a later replacement.
 
The escapement and regulator remain undocumented. Cal. 620, its immediate derivative, uses a straight-line lever and changes from a micrometer regulator to an index regulator, but those details cannot be assigned to Cal. 600 without direct evidence. Shock protection is more likely absent: the factory table flags it on the 1950 calibers in this branch but not on Cal. 600, whose design predates Incabloc production in 1938.


<span id="cal-630"></span>
<span id="cal-a260"></span>
=== Cal. 630 ===
=== Cal. A260 ===
[[File:Cal 630 movement.webp|thumb|right|220px|Cal. 630, EmmyWatch]]
[[File:Cal A260 movement.webp|thumb|right|220px|Cal. A260-era movement, engraved Rolex Self Winder, Jewels, Patented]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
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|-
|-
| jewels
| jewels
| 17
| 19
|-
|-
| frequency
| frequency
| 18,000 vph (2.5 Hz)
| 18,000 vph (2.5 Hz)
|-
| power reserve
| 36h
|-
|-
| size
| size
| 26.0mm
| 26.4mm
|-
|-
| escapement
| escapement
Line 384: Line 457:
|-
|-
| balance
| balance
| Monometallic
| Superbalance, blued Breguet spring
|-
| shock
| Present (unnamed brand)
|}
|}


Launched 1937, 26.0mm, 17 jewels (Grail Watch Wiki gives 17; WatchGuys lists 18 for the same caliber, a documented count discrepancy between sources), COSC-certified, adjusted to 7 positions, Breguet hairspring. Evolved directly from the Cal. 620 base (Caliber Corner groups 620, 630, 635, and 645 as one related family), and shares its predecessor's cover-plate marking: "Vis Tirette *** Patented *** Trigger Screw." The rotor and bridge carry the same "Rolex Perpetual Chronometer, Swiss Made, Patented, Super-Balance" signature as the 620, which makes the two easy to mix up without checking the caliber number stamped in the small box on the bridge itself.
A260 powered the first Submariner references, 6204 and 6205, from 1953 to 1955. "A.260" is Rolex's size-family code for this movement class, comparable to the Prince family's "T.S." code. Its non-butterfly rotor distinguishes it from the butterfly-rotor Cal. 1030. Hodinkee traces A260 to a movement used in earlier Oyster Perpetuals and later Bubblebacks, predating its Submariner fitment.


<span id="cal-105-hunter"></span>
<span id="cal-a296"></span>
=== Cal. 10½ Hunter ===
=== Cal. A296 ===
[[File:Cal A296 movement.webp|thumb|right|220px|Cal. A296-era rotor component, engraved Rolex Perpetual Chronometer]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 396: Line 473:
|-
|-
| type
| type
| Manual
| Automatic
|-
|-
| jewels
| jewels
| 17–18
| 18
|-
|-
| frequency
| frequency
| 18,000 vph (2.5 Hz)
| 18,000 vph (2.5 Hz)
|-
| power reserve
| 36h
|-
|-
| size
| size
| 10½ lignes
| 29.5mm
|-
|-
| escapement
| escapement
Line 411: Line 491:
|-
|-
| balance
| balance
| Superbalance, 6-position
| Monometallic Superbalance
|-
|-
| regulator
| regulator
| Swan-neck micrometer
| Index
|-
| shock
| Shock absorber (775-labelled lots only)
|}
|}


An Aegler-supplied 10½-ligne hand-wound family, 700 / 710 base architecture: straight-line lever escapement, monometallic Superbalance adjusted to 6 positions, self-compensating Breguet balance spring, swan-neck micrometer regulator — the chronometer-grade fitting, per Antiquorum's own cataloguing of both a bare Cal. 700 movement and a cased 10½-ligne hunter example — and no shock protection named. It powers the originating Air-King 4925 and its Air-Lion / Air-Tiger / Air-Giant siblings — the 4365 sub-seconds, 4444 mid-size, and 4647 Hunter Precision — sitting architecturally between the pre-war Prince and Bubbleback shaped calibers and the post-war 1030 automatic. Rolex's own factory caliber table dates 700 and 710 to 1938 rather than the wider 1945-53 window sometimes quoted, and lists Cal. 720 separately as an automatic with shock protection — a different caliber from this manual pair, not a third member of it, contra how this family is sometimes grouped.
Made from 1952 to 1955, A296 powered the Big Crown 6200, early Explorers 6098, 6150 "Precision," 6298, and 6350, and early Datejusts 6104 and 6105. Its full rotor winds in one direction; it is not a bumper caliber. The 6150 and 6350 use the same movement in non-COSC and COSC forms. "A.296" is Rolex's size-family code and 775 its commercial number, so listings may use either designation for the same movement. Cal. 1030 replaced it in 1955 with bidirectional winding, a butterfly rotor, and a thinner automatic module. Phillips identifies that reduced thickness as the change that eliminated the domed Bubbleback caseback.
 
The movement has a straight-line lever escapement, monometallic balance, self-compensating Breguet balance spring, and index regulator. Catalogues using the commercial number 775 also specify six-position adjustment and a shock absorber, and Rolex's factory table marks ref. 775 as shock-protected. The two designations refer to the same build. The factory table also assigns A.296 to Cal. 765, showing that the size code covers more than one commercial caliber.


<span id="cal-600"></span>
Christie's describes a 6150 balance as a "patented Super-balance," linking it to Aegler patent CH196706 and the recessed timing screws used on [[#cal-300|Cal. 300]]. Published jewel counts vary because some catalogues separate the going train from the automatic module. Figures of 18 and 19 appear for the base movement, with another two or seven assigned to the rotor module. One 6150 is described as a 19-jewel movement with a two-jewel automatic module. The factory table's figure of 18 counts the base plate alone.
=== Cal. 600 ===
 
<span id="cal-645"></span>
=== Cal. 645 ===
[[File:Cal 645 movement.webp|thumb|right|220px|Cal. 645 winding bridge, engraved "Rolex Perpetual Chronometer, Super-Balance, Patented" — EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 426: Line 514:
|-
|-
| type
| type
| Manual
| Automatic
|-
|-
| jewels
| jewels
| 17
| 17&ndash;20
|-
|-
| frequency
| frequency
| Not recorded
| 18,000 vph (2.5 Hz)
|-
|-
| power reserve
| power reserve
| Not recorded
| 41h
|-
|-
| size
| size
| 9&frac34; lignes / 21.7mm
| 26.4mm
|-
|-
| escapement
| escapement
| Not recorded &mdash; Cal. 620 derivative is straight-line lever
| Straight-line lever
|-
|-
| balance
| balance
| Patented Super Balance
| Superbalance, timed to 6 positions
|-
|-
| regulator
| regulator
| Not recorded &mdash; Cal. 620 derivative is micrometer, later index
| Index
|-
|-
| shock
| shock
| None documented
| Shock absorber
|}
|}


A 9&frac34;-ligne manual caliber, one size class below the 10&frac12;-ligne 700/710/720 family above, fitted with a patented Super Balance. Sotheby's November 2025 sale of the Mercedes Gleitze Oyster ($1.73 million, via Robb Report) catalogues the movement as a Hunter-architecture base upgraded to Cal. 600, rhodium-finished, in a 27mm case made in late 1926 &mdash; the watch Gleitze wore on her 21 October 1927 Channel swim attempt, caseback engraved "Miss M. Gleitze / The Companion 'Oyster.' Vindication Channel Swim. October 21st. 1927."
Cal. 645 belongs to the Cal. 600 family and shares the A.260 size code with Cal. 635. The distinctions are functional: Cal. 630 has sweep seconds without shock protection, Cal. 635 has small seconds with shock protection, and Cal. 645 combines sweep seconds with shock protection. Cal. 645 powered the semi-Bubbleback Oyster Perpetual refs 6084, 6085, and 6284 around 1948–1953. Auction catalogues give 17 to 20 jewels, consistent with both differing counting conventions and market-specific tariff variants found elsewhere in the family.


Rolex's factory caliber table lists Cal. 600 as a Basic Caliber rather than a derivative &mdash; manual wind, small seconds, 21.7mm, 17 jewels, entered 1933, under a Hunter-patent size bracket. Basic Caliber is the load-bearing word: 600 is the root the whole 9&frac34;-ligne automatic branch grows from, with Cal. 620 (1936) taken directly off it and 635, 640 and 645 (all 1950) descending through that line. The 17-jewel count is one of the few figures in this part of the catalogue that two independent sources agree on outright, the factory table and Sotheby's Gleitze lot giving the same number.
The movement uses a straight-line lever escapement, Superbalance adjusted to six positions, shock absorber, self-compensating Breguet balance spring, and index regulator. Some catalogues use "monometallic balance timed to 6 positions" instead of Superbalance. Both terms describe a monometallic balance with recessed timing screws.


The 1933 date is what makes the Gleitze watch interesting rather than simply old. The case carries Glasgow import marks for 1926/1927 and the swim was October 1927, but the caliber inside is one the factory table does not start until 1933, and the Super Balance stamped on it belongs to Aegler's Swiss patent CH196706, not filed until August 1936 and not granted until March 1938. The movement in that watch is therefore a later service replacement by a decade or more, which squares with the mid-1970s Rolex service box that accompanied the lot. The provenance is the case and the engraving; the movement is a survivor of Rolex's own aftercare.
Rolex's factory table gives the lineage as Cal. 600 to 635 to 645. It places Cal. 635, 640, and 645 under the A.260 size code at 26.4mm and 18 jewels, all entered in 1950 and all shock-protected. The shock system separates this 1950 A.260 group from the 1936 Cal. 620 base.


Two of the four mechanical fields stay open here, and the sources do not close them. No 600-specific lot description names the escapement or the regulator, and the factory table has no column for either. Its immediate derivative Cal. 620 is documented as a straight-line lever with a micrometer regulator on earlier examples giving way to an index later, which is the closest the record comes without guessing. Shock protection is a firmer negative: the factory table flags shock-protecting construction on the 1950 calibers in this branch and does not flag it on the 600, consistent with a design fixed years before Incabloc reached production in 1938.
Jewel counts also vary according to whether a catalogue includes the automatic module. Bonhams describes the related [[#cal-745|Cal. 745]] as "18 jewels plus 7 rotor jewels." Its 20-jewel description of a Cal. 645 in a 6085, against the factory table's 18, does not necessarily indicate a different movement.


<span id="cal-a260"></span>
<span id="cal-740"></span>
=== Cal. A260 ===
=== Cal. 740 ===
[[File:Cal A260 movement.webp|thumb|right|220px|Cal. A260-era movement, engraved Rolex Self Winder, Jewels, Patented]]
[[File:Cal 740 movement.webp|thumb|right|220px|Cal. 740 in a reference 4467 Datejust, case back removed, rotor engraved "Rolex Perpetual Chronometer, Super Balance, Vis Tirette"]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
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|-
|-
| jewels
| jewels
| 19
| 18 base plate (26 in Antiquorum lots &mdash; see note)
|-
|-
| frequency
| frequency
Line 478: Line 566:
|-
|-
| power reserve
| power reserve
| 36h
| Not recorded
|-
|-
| size
| size
| 26.4mm
| 29.5mm
|-
|-
| escapement
| escapement
Line 487: Line 575:
|-
|-
| balance
| balance
| Superbalance, blued Breguet spring
| Superbalance, adjusted to 6 positions
|-
| regulator
| Index (A.295-labelled lots)
|-
|-
| shock
| shock
| Present (unnamed brand)
| Not named in 740 lot text
|}
|}


1953–55, 19 jewels, 18,000 vph, 36 hours of reserve, 26.4mm — the caliber in the first Submariner references, 6204 and 6205. Straight-line lever escapement, monometallic Superbalance, blued-steel self-compensating Breguet overcoil, index regulator, shock absorber — confirmed across Antiquorum and Sotheby's lot descriptions of both references. "A.260" is itself Rolex's size-family code for this movement class rather than a caliber number in the ordinary sense, which is why auction houses write "cal. A260" the same way they write "cal. T.S." for the Prince family. Its rotor is "non-butterfly," visually distinct from the butterfly-rotor Cal. 1030 that follows it. Hodinkee describes A260 as repurposed from earlier Oyster Perpetual models including later Bubblebacks, rather than a clean-sheet design for the Submariner.
Cal. 740 powered the original Datejust ref. 4467, introduced in 1945 with Rolex's first automatic wristwatch date mechanism. It uses the 720/730 base architecture and the A.295 size code, the earlier sibling of the A.296 group.
 
The 10&frac12;-ligne rhodium-plated movement has a straight-line lever escapement, Superbalance adjusted to six positions, and self-compensating Breguet balance spring. Some catalogues substitute "monometallic balance adjusted to 6 positions" for Superbalance, as they do for Cal. 645. No Cal. 740 description names the regulator; the related A.295-coded movement in ref. 6075 uses an index regulator.
 
The jewel count differs by convention. Antiquorum gives 26, while Rolex's factory table gives 18; the higher figure likely includes the winding module, as Bonhams itemises the related [[#cal-745|Cal. 745]] as "18 jewels plus 7 rotor jewels."
 
The production date remains unresolved. Rolex's factory table enters Cal. 740 in 1950 and its Cal. 720 and 730 bases in 1945, five years after the ref. 4467 launch. Early 4467s may have used a 720-series movement before Cal. 740 arrived, or the table date may be wrong. Published descriptions of surviving 4467s do not settle the sequence.
 
Shock protection is unconfirmed. The factory table flags it for Cal. 720 and 730 but not Cal. 740, and ref. 4467 catalogue descriptions do not mention a shock absorber. These omissions suggest an unprotected balance but do not prove it.


<span id="cal-a296"></span>
<span id="cal-745"></span>
=== Cal. A296 ===
=== Cal. 745 ===
[[File:Cal A296 movement.webp|thumb|right|220px|Cal. A296-era rotor component, engraved Rolex Perpetual Chronometer]]
[[File:Cal 745 movement.webp|thumb|right|220px|Cal. 745, gilt rotor engraved "Rolex Perpetual Chronometer, Super Balance" — EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 506: Line 605:
|-
|-
| jewels
| jewels
| 18
| 18 + 7 rotor
|-
|-
| frequency
| frequency
Line 512: Line 611:
|-
|-
| power reserve
| power reserve
| 36h
| 42h
|-
|-
| size
| size
Line 521: Line 620:
|-
|-
| balance
| balance
| Monometallic Superbalance
| Superbalance
|-
|-
| regulator
| regulator
Line 527: Line 626:
|-
|-
| shock
| shock
| Shock absorber (775-labelled lots only)
| Shock absorber
|}
|}


1952&ndash;55, 18 jewels, 18,000 vph, 36 hours, 29.5mm, a full-rotor uni-directional Perpetual, not a bumper caliber despite sometimes being described as one &mdash; a confusion with Bubbleback-era geometry. A296 powers the Big Crown 6200 and the earliest Explorers (6098, 6150 "Precision," 6298, 6350), and the earliest Datejusts, 6104 and 6105, with the 6150 and 6350 showing the identical movement in non-COSC and COSC form. Some auction and dealer listings write "Cal. 775" instead of "Cal. A296" for the same movement on the same watches &mdash; A.296 is Rolex's size-family code and 775 the commercial number, not two different calibers. Cal. 1030 succeeds it from 1955 with bidirectional winding via a butterfly rotor and a thinner autowind module; that thickness reduction is specifically what eliminates the domed Bubbleback caseback profile going forward &mdash; Phillips' Geneva Watch Auction FOUR framed the A296-to-1030 swap explicitly as a thickness change, not a different winding concept.
Cal. 745 adds a calendar to Cal. 740 and shares balance-staff and stem parts with the 700/710/720/730/740/760/765/775 family. Rolex's factory table assigns it the A.295 size code and a 1950 entry date. It is based on the 720–740 architecture; Cal. 740 has no calendar.
 
Bonhams describes a Cal. 745 in a ref. 6305 as rhodium-plated, with 18 jewels plus seven rotor jewels, a straight-line lever escapement, Superbalance, shock absorber, self-compensating blued-steel Breguet balance spring, and index regulator. Separating the base movement from the winding module explains why totals of 18, 25, and 26 appear for the same build. The blued-steel balance spring is also a period marker, preceding the white-metal springs seen later.
 
Cal. 745 appears in the Datejust "Ovettone" group. Documented examples include a circa 1955 18K yellow-gold ref. 6305, case 97602; a ref. 6105 with 1952 Glasgow import marks and movement H78230; and a circa 1955 ref. 6304 with movement 99698/H46452. Other ref. 6105 examples use A296, placing the reference across the boundary between the A.295 and A.296 groups. The claimed Cal. 745 fitment in ref. 6039 is unverified; no supporting lot description or confirmed Rolex ref. 6039 has been identified.


The mechanical description repeats almost verbatim wherever a house catalogues the movement under its size code: straight-line lever escapement, monometallic balance, self-compensating Breguet balance spring, index regulator. Bonhams gave exactly that for a 6105 in London in May 2013, Sotheby's for another 6105 in Geneva in May 2010, and Antiquorum for a 6104. Lots catalogued under the commercial number 775 add two things the A.296-labelled ones leave out &mdash; a balance adjusted to 6 positions and a shock absorber &mdash; and they add them consistently: Antiquorum in New York in December 2009, Sotheby's in New York in June 2006 and Artcurial in Monaco in July 2013 all list both for 6350 Explorers, and Rolex's own factory caliber table flags REF. 775 as shock-protecting. The split tracks which designation the cataloguer reached for rather than two builds of the movement. That same factory table settles the size-code question from the other direction by putting A.296 on Cal. 765 as well, the calendar-equipped version at the same 29.5mm and 18 jewels &mdash; a size code covering two commercial numbers, which is what a size code is supposed to do.
<span id="precision-family"></span>
== Oyster and Oysterdate Precision ==


Balance metallurgy is where the caliber connects back to the Prince era. Christie's, describing a 6150 in Hong Kong in November 2007, calls the balance a "patented Super-balance," the same Aegler patent CH196706 that governs [[#cal-300|Cal. 300]]'s recessed timing screws, filed in August 1936 and granted in March 1938. Jewel counts printed for the movement scatter badly and should not be read as variants: 18 and 19 turn up for the going train, 2 and 7 for the rotor module, and one Christie's description of a 6150 spells the arithmetic out as a 19-jewel movement with a 2-jewel auto module. The factory table's figure, 18, counts the base plate alone.
Precision is Rolex's non-chronometer manual line, a 10½-ligne family built alongside the automatic Bubblebacks. The Oysterdate Precision 6694 remained in production through the end of the 1980s, a year beyond the hand-wound Daytona; one surviving lot includes a 1990/1991 Rolex calendar card. Rolex continued making manual-wind watches after the 6694: the Cellini Danaos used Cal. 1602 into 2008, and the chronometer-certified Cellini Prince used Cal. 7040 until about 2015. The small-seconds Cal. 1240 also carried this architecture into the platinum Cellinium 5240 and 5241. Seconds placement, date and beat rate distinguish the seven commercial numbers. Rolex's parts plates identify Cal. 1210 as the base for 1200, 1215, 1220, 1225 and 1240.


<span id="cal-645"></span>
<span id="cal-1210"></span>
=== Cal. 645 ===
=== Cal. 1210 ===
{| class="wikitable" style="width:280px; font-size:90%;"
[[File:Cal 1210 movement.webp|thumb|right|220px|Cal. 1210 in a 1960 Oysterdate Precision ref. 6466, movement in case]]
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
! value
! value
|-
|-
| type
| type
| Automatic
| Manual
|-
|-
| jewels
| jewels
| 17&ndash;20
| 18 (factory plate) · 17 (as signed and catalogued)
|-
|-
| frequency
| frequency
Line 552: Line 657:
|-
|-
| power reserve
| power reserve
| 41h
| ~58h
|-
|-
| size
| size
| 26.4mm
| 10½′′′ / Ø23.80mm × 4.27mm height
|-
|-
| escapement
| escapement
| Straight-line lever
| Straight-line lever, jewelled pallet fork
|-
|-
| balance
| balance
| Superbalance, timed to 6 positions
| Glucydur, screwed rim, Breguet overcoil
|-
|-
| regulator
| regulator
| Index
| Index with movable stud support
|-
|-
| shock
| shock
| Shock absorber
| KIF-pattern, balance and escape wheel
|}
|}


A sibling of Cal. 630 sharing the same base Cal. 600 architecture and A.260 size code as Cal. 635 above it, distinguished by function rather than grading tier: 630 is sweep-seconds without shock protection, 635 is small-seconds with shock protection, 645 is sweep-seconds with shock protection. Powers the semi-Bubbleback Oyster Perpetual 6084, 6085, and 6284, roughly 1948-1953. Jewel counts vary 17-20 across auction listings for the same caliber, consistent with market-specific tariff variants documented elsewhere in this family.
Rolex's parts plates identify Cal. 1210 as the family's architectural base and file the small-seconds 1200 as a derivative. The parts plates support Horbiter's identification of Cal. 1210 as the base; Fratello names Cal. 1200.
 
The jewel count remains unclear. Rolex specifies 18 jewels for the two no-date calibers and 17 for the date versions, yet known movements are signed "Seventeen Jewels" and major-house catalogues consistently give 17. Both counts are documented, but their distribution among watches has not been established. Contemporary American import duties taxed jewel count and also account for the "UNADJUSTED" stamps found on some movements.


Four houses describe the movement in near-identical terms, which for a caliber this obscure is unusually good coverage: straight-line lever escapement, Superbalance timed to 6 positions, shock absorber, self-compensating Breguet balance spring, index regulator. Bonhams gave that reading twice, in Knightsbridge in December 2005 for a 6284 and in New York in June 2008 for a 6085; Sotheby's matched it in New York in June 2007, again for a 6085; and Gros &amp; Delettrez in Paris in November 2009 catalogued a 6284 the same way, swapping "monometallic balance timed to 6 positions" for the Superbalance wording. The two phrasings describe the same part &mdash; Superbalance is a monometallic balance with recessed timing screws, not a separate metallurgy.
The balance is Glucydur with a Breguet overcoil, as specified on the sibling Cal. 1200 plate. Regulation uses a conventional index and movable stud, with adjusting washers in five thicknesses. It is not free-sprung; Rolex reserved Microstella for its 12½-ligne chronometers.


Rolex's factory caliber table sharpens the lineage a step beyond the sibling framing above. It gives Cal. 635 as 645's immediate base and Cal. 600 as the root that 635 itself descends from, so the family reads 600 to 635 to 645 rather than 645 branching straight off the root. The table also puts the A.260 size code on 635, 640 and 645 together at 26.4mm and 18 jewels, all three entered in 1950, and flags every one of them shock-protecting &mdash; the feature that separates the 1950 A.260 group from the 1936-vintage Cal. 620 base is the shock system, and the table records it that way explicitly.
The pallet fork runs in jewels, while the escape wheel has shock-mounted settings and cap jewels on both pivots, matching the treatment of the balance. Indirect centre seconds, driven from the fourth wheel through a friction-sprung pinion, can produce seconds-hand flutter even in a healthy movement. The earliest examples may lack shock protection; Antiquorum's 1946 ref. 4560 description names none.


The jewel spread has a second explanation running alongside the tariff-variant one. Catalogues in this family sometimes quote the base-plate count and sometimes the total including the winding module, and occasionally itemise both: Bonhams describes the closely-related [[#cal-745|Cal. 745]] as "18 jewels plus 7 rotor jewels" in so many words. A Bonhams listing giving a 6085 "Calibre 645, 20 jewels, superbalance" against the factory table's 18 is the same arithmetic seen from either end, not necessarily a different movement.
Documented fitments include refs. 3745, 4560, 6420, 6422, 6426/6427, 6466, 6480, 6482, 6494, 9083 and 9659. Bonhams also records a ref. 6694 with a III.60 caseback date on Cal. 1210. Ref. 6082 is disputed: Crott assigns one example to 1210, while Antiquorum and EveryWatch catalogue the reference with Cal. 710.


<span id="cal-740"></span>
<span id="cal-1215"></span>
=== Cal. 740 ===
=== Cal. 1215 ===
[[File:Cal 1215 movement.webp|thumb|right|220px|Cal. 1215 in a movement holder, from a 1962 Oyster Date Precision ref. 6694 service]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 585: Line 693:
|-
|-
| type
| type
| Automatic
| Manual
|-
|-
| jewels
| jewels
| 18 base plate (26 in Antiquorum lots &mdash; see note)
| 17
|-
|-
| frequency
| frequency
Line 594: Line 702:
|-
|-
| power reserve
| power reserve
| Not recorded
| ~58h
|-
|-
| size
| size
| 29.5mm
| 10½′′′ / Ø23.80mm × 5.07mm height
|-
|-
| escapement
| escapement
Line 603: Line 711:
|-
|-
| balance
| balance
| Superbalance, adjusted to 6 positions
| Glucydur, Breguet overcoil (via base 1210) · flat in one lot
|-
|-
| regulator
| regulator
| Index (A.295-labelled lots)
| Index with movable stud support
|-
|-
| shock
| shock
| Not named in 740 lot text
| KIF-pattern
|-
| date
| Non-quickset, dragging change
|}
|}


The caliber behind the original Datejust: introduced 1945 with reference 4467, carrying Rolex's first automatic date mechanism in a wristwatch. Base architecture 720/730, size code A.295 &mdash; the slightly earlier sibling of the A.296 group above.
Cal. 1215 adds a calendar to the 1210, increasing movement height from 4.27mm to 5.07mm. Its two-page parts sheet covers only the calendar mechanism and defers the rest to Cal. 1210. Date discs came in champagne, silvered, and champagne with red-and-black printing.


Antiquorum has catalogued the movement in the 4467 twice in near-identical language, in Geneva in November 2002 and in Hong Kong in June 2002: rhodium-plated, straight line lever escapement, Superbalance adjusted to 6 positions, self-compensating Breguet balance-spring, at 10&frac12; lignes. A third description of the same caliber substitutes "monometallic balance adjusted to 6 positions" for the Superbalance wording, the same interchangeable pair seen on Cal. 645. No 740 lot description names a regulator, but the A.295-coded movement in reference 6075 is catalogued with an index regulator, which is the nearest documented neighbour.
The hairspring is disputed. The parts plates imply the 1210's Breguet overcoil because the 1215 sheet specifies no separate balance. Antiquorum describes one ref. 9996 with a flat hairspring and index regulator, but uses Breguet wording elsewhere. No catalogue describes the caliber as free-sprung.


Two numbers in the record refuse to reconcile, and both are worth carrying rather than choosing between. The first is the jewel count: those Antiquorum lots give 26, Rolex's factory caliber table gives 18. The counting convention explains it &mdash; Bonhams itemises the sister [[#cal-745|Cal. 745]] as "18 jewels plus 7 rotor jewels," so a catalogue quoting the mid-twenties is counting the winding module and the factory figure is not. The second is harder. The factory table enters Cal. 740 in 1950 and its 720 and 730 base calibers in 1945, which puts the caliber five years behind the 4467's own 1945 launch. Either the earliest 4467s left with a 720-series movement and the 740 arrived partway through the reference's run, or the table's date is wrong. Nothing in the published record decides between them, and lot descriptions for surviving 4467s name the 740 without addressing when it went in.
The non-quickset date moves over roughly forty minutes and seats at the end of the change. A pawl on the calendar wheel engages a star wheel beneath the date disc before the jumper spring seats it. Rolex used the same arrangement in the 7xx, 1035 and 11xx families; instantaneous change arrived with the 1065/1066 and 15xx calibers. A date change beginning around 11:20 is normal for this mechanism.


One absence carries its own weight. The factory table flags both 720 and 730 as shock-protecting and does not flag the 740, and the 4467 lot descriptions likewise stop at the balance spring without mentioning a shock absorber &mdash; in a catalogue style that names shock systems when they are there. That points to an unprotected balance, though a negative drawn from two silences is weaker than a positive drawn from a movement in hand, and it should stay unconfirmed until one is examined.
Christie's places the ref. 6494 changeover between a circa-1956 example with Cal. 1210 and a circa-1958 example with 1215. Other documented fitments include the Speedking 6430, early 6694 production, and refs. 9996/9919. Refs. 6094 and 6294 used Cal. 740 and 790 respectively, rather than 1215.


<span id="cal-745"></span>
<span id="cal-1216"></span>
=== Cal. 745 ===
=== Cal. 1216 ===
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 627: Line 738:
|-
|-
| type
| type
| Automatic
| Manual (assumed, by family)
|-
|-
| jewels
| jewels
| 18 + 7 rotor
| not documented
|-
|-
| frequency
| status
| 18,000 vph (2.5 Hz)
| Number attested in the parts trade only
|}
 
Almost nothing is known about Cal. 1216. The common description of it as a 17-jewel Cal. 1215 variant has no traceable support.
 
Rolex's surviving parts plates cover 1200, 1210, 1215, 1220, 1225 and 1240, but omit 1216. No major-house lot identifies a Rolex Cal. 1216, and Heritage's apparent example is a case reference. Confusion is also possible with Ronda's contemporary 1216 movement.
 
The parts trade nevertheless records it as a Rolex number. Cas-Ker's genuine-parts catalogue places 1216 between 1215 and 1220 and lists crown-wheel screw 1216.5420, following Rolex's caliber-prefixed numbering convention.
 
The parts catalogue attests the Cal. 1216 designation. Its jewel count, seconds layout, beat rate and fitments remain unknown. Published specifications derived from the 1215 are unconfirmed.
 
<span id="cal-1220"></span>
=== Cal. 1220 ===
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! value
|-
| type
| Manual
|-
| jewels
| 18 (factory plate) · 17 (as signed)
|-
| frequency
| 21,600 vph (3 Hz)
|-
|-
| power reserve
| power reserve
| 42h
| ~58h
|-
|-
| size
| size
| 29.5mm
| 10½′′′ / Ø23.80mm × 4.27mm height
|-
|-
| escapement
| escapement
Line 645: Line 780:
|-
|-
| balance
| balance
| Superbalance
| Screwless, inertia blocks, flat hairspring
|-
|-
| regulator
| regulator
| Index
| Index with movable stud support
|-
|-
| shock
| shock
| Shock absorber
| KIF-pattern
|}
|}


A calendar-equipped update to Cal. 740, sharing a balance-staff and stem parts group with the whole 700/710/720/730/740/760/765/775 family. Rolex's factory caliber table gives it the A.295 size code, 29.5mm, 18 jewels, entered 1950, built off a 720-740 base and specified as self-winding with sweep seconds and a calendar &mdash; the date complication is the whole point of the number, since the 740 beneath it is a chronometer sweep-seconds movement with no calendar work.
Cal. 1220 raises the 1210 platform to 21,600 vph and uses a different oscillator. Both its parts plate and the 1978 third edition of Rolex's ''Technical and Service Information'' give that rate. The sometimes-published 19,800 vph figure is unsupported.


The single most useful description comes from Bonhams in February 2014, cataloguing a reference 6305: rhodium-plated, 18 jewels plus 7 rotor jewels, straight-line lever escapement, Superbalance, shock absorber, self-compensating blued steel Breguet balance-spring, index regulator. That one line covers all four mechanical fields, and the itemised jewel count is the key that unlocks the rest of this family's arithmetic &mdash; it is the only description in the group that separates the base plate from the winding module instead of publishing one merged figure, which is why counts of 18, 25 and 26 all circulate for movements of the same build. Blued steel for the balance spring rather than the white metal seen later is a period marker in its own right.
The higher-beat generation replaces the 1210's screwed Glucydur balance and Breguet overcoil with a smooth-rimmed balance and flat hairspring. Gilt and nickel-plated inertia blocks provide about ten seconds per day of fine adjustment across their range; the index handles larger corrections. Separate regulator, stud-support and regulating-stud parts confirm that this is an index-regulated movement, not a free-sprung one.


The references it appears on in the auction record are the Datejust "Ovettone" group. A 6305 in 18K yellow gold, case 97602, circa 1955, is catalogued with an 18-jewel Cal. 745; a 6105 carrying Glasgow import marks for 1952 gives the same 18-jewel Cal. 745, movement H78230; and a 6304 from circa 1955, movement 99698/H46452, gives it again. Reference 6105 is the interesting one, because other lots for that same reference are catalogued under Cal. A296 instead &mdash; the 6105 sits on the boundary between the A.295 and A.296 size groups and the auction record splits accordingly. An attribution of Cal. 745 to reference 6039 also circulates, but no lot description supports it and 6039 does not surface as a Rolex reference anywhere in the auction record. It should be read as unverified.
Cal. 1220 appears mainly in the oversize ref. 8029, but its dates conflict. Phillips gives 1950, Antiquorum dates case 714105 to about 1951, and Sotheby's dates that same case to about 1961 without naming its caliber. The earlier dates sit awkwardly beside the later-1960s siblings and remain unresolved. Claims that 1220 movements were commonly signed 1225, including those in later ref. 6426 production, are unverified.


<span id="precision-family"></span>
<span id="cal-1225"></span>
== Oyster and Oysterdate Precision ==
=== Cal. 1225 ===
 
[[File:Cal 1225 movement.webp|thumb|right|220px|Cal. 1225 in a ref. 6694 Oysterdate Precision, bridges marked "Montres Rolex S.A. Swiss"]]
Precision is Rolex's non-chronometer manual line, a 10½-ligne family built alongside the automatic Bubbleback generation rather than after it, and the line that closed out hand winding inside the Oyster case — the Oysterdate Precision 6694 ran to the end of the 1980s, a year past the hand-wound Daytona, and an auction lot survives with its original box and a 1990/1991 Rolex calendar card. The wider claim attached to the 6694, that it is the last manual-wind Rolex of any kind, does not survive checking. It traces to dealer copy rather than to any Rolex document, and Rolex kept selling manual-wind watches for two more decades: the Cellini Danaos on Cal. 1602 into 2008, and the Cellini Prince on Cal. 7040, introduced in 2005 and discontinued a decade later, which unlike anything in this family was a certified chronometer. This family's own architecture outlived the Oysterdate too, in the small-seconds Cal. 1240 that ran the platinum Cellini Cellinium 5240 and 5241. Seven commercial numbers cover the group, distinguished by seconds placement, date, and beat rate rather than by separate architectures, and Rolex's surviving factory parts plates head every one of them — 1200, 1215, 1220, 1225 and 1240 — with the words "Base Calibre 1210."
 
<span id="cal-1210"></span>
=== Cal. 1210 ===
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 675: Line 806:
|-
|-
| jewels
| jewels
| 18 (factory plate) · 17 (as signed and catalogued)
| 17
|-
|-
| frequency
| frequency
| 18,000 vph (2.5 Hz)
| 21,600 vph (3 Hz)
|-
|-
| power reserve
| power reserve
Line 684: Line 815:
|-
|-
| size
| size
| 10½′′′ / Ø23.80mm × 4.27mm height
| 10½′′′ / Ø23.80mm × 5.07mm height
|-
|-
| escapement
| escapement
| Straight-line lever, jewelled pallet fork
| Straight-line lever
|-
|-
| balance
| balance
| Glucydur, screwed rim, Breguet overcoil
| Screwless, inertia blocks, flat hairspring
|-
|-
| regulator
| regulator
Line 696: Line 827:
|-
|-
| shock
| shock
| KIF-pattern, balance and escape wheel
| KIF
|-
| date
| Non-quickset, dragging change
|}
|}


Rolex's own parts plates settle the family tree. The sheet for every other member — 1200, 1215, 1220, 1225 and the later 1240 — is headed "Base Calibre 1210," and the 1210's sheet is headed with its own number. Fratello and Horbiter disagree in print over whether Cal. 1200 or Cal. 1210 is the architectural base of the group; the factory documentation reads for the 1210, with the small-seconds 1200 filed as a derivative rather than an ancestor.
Cal. 1225 adds a calendar to the 1220 and carried the Oysterdate Precision 6694 through its final years. Rolex's plate specifies a timed flat hairspring with gilt and nickel-plated inertia blocks, consistent with Antiquorum's descriptions of refs. 6426 and 6694. Published claims of a Breguet overcoil conflict with the factory plate and auction record. Bonhams' reference to a "Gyromax balance" is a cataloguing error; Gyromax is Patek Philippe's free-sprung system.


The plate gives Ø23.80mm and 4.27mm high, 18,000 vph, centre seconds, 18 jewels. That last figure is the family's standing oddity: Rolex specifies 18 jewels for the two no-date calibers and 17 for the two date calibers, while the movements themselves are signed "Seventeen Jewels" and every catalogued lot found across Antiquorum, Christie's, Sotheby's, Bonhams and Phillips reads 17 without a single exception. Both executions are documented; nothing found reconciles which watches got which, though the same period saw Rolex stamp some movements "UNADJUSTED" purely to sit under a lower American import duty, and jewel count was taxed on the same schedule.
Rolex used "Precision" on uncertified manual and automatic movements, including the Air-King 5500. On Cal. 1225, the "UNADJUSTED" stamp records an import-duty classification.


Antiquorum's cataloguing formula for the caliber runs "straight-line lever escapement, monometallic balance, shock absorber, self-compensating Breguet balance spring," repeated word for word across lots dated from 1946 into the 1970s. Rolex's bilingual plate for the sibling Cal. 1200 names the material outright — a Glucydur balance, supplied either bare and pivoted or complete with Breguet hairspring and regulated. Regulation is conventional index-and-stud with adjusting washers in five thicknesses, not free-sprung; Rolex's own ''Technical and Service Information'' reserves the Microstella system for its 12½-ligne chronometers, which this caliber is not.
The caliber does not hack. The 1210 parts plate contains no stop lever or hack spring, and Rolex's 1978 service book covers hacking only for the late 1500 series and the 2030/2035.


The plate turns up two details the secondary literature misses. The escapement is more thoroughly jewelled than the price class suggests — the pallet fork runs in jewels, and the escape wheel sits in shock-mounted settings with cap jewels on both pivots, the same treatment given the balance. And the centre seconds is indirect, driven off the fourth wheel through a friction-sprung pinion, which is why a perfectly healthy example can show a fluttering seconds hand. The earliest movements carry no shock protection at all: Antiquorum's 1946 ref. 4560 lot, which also supplies the family's only catalogued ligne size at 10½′′′, describes the movement without one.
Recurring service faults include worn pendant-tube and crown threads, winding stems and mainsprings, plus water-damaged date rings. The early Oysterdate calendar is the movement's weak point, though the pallet fork is fully polished and its jewels lightly undercut. Rolex service centres still accept these calibers; one 1974 example returned from overhaul running two seconds per day with a measured 57-hour reserve.


Auction lots place the caliber in refs 3745, 4560, 6420, 6422, 6426/6427, 6466, 6480, 6482, 6494, 9083 and 9659, and — against the shorthand pairing the 6694 only with later calibers — Bonhams catalogues a 6694 with a III.60 caseback date on Cal. 1210. An early Crott-catalogued ref. 6082 is also given to this caliber, though Antiquorum and EveryWatch both catalogue 6082 examples on Cal. 710 instead.
Documented fitments include refs. 6426, 6466 and, most often, 6694 from the late 1960s through at least 1979. Comparison of a 1966 ref. 6694 with Cal. 1215 and a 1973 example with 1225 places the changeover around 1967.


<span id="cal-1215"></span>
<span id="cal-1200"></span>
=== Cal. 1215 ===
=== Cal. 1200 ===
[[File:Cal 1200 movement.webp|thumb|right|220px|Cal. 1200, bridges marked "Montres Rolex S.A. Geneva Swiss, Seventeen 17 Jewels", from a Rolex Precision service]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 728: Line 863:
|-
|-
| size
| size
| 10½′′′ / Ø23.80mm × 5.07mm height
| 10½′′′ / Ø23.80mm × 3.65mm height
|-
|-
| escapement
| escapement
| Straight-line lever
| Straight-line lever, jewelled pallet fork and staff
|-
|-
| balance
| balance
| Glucydur, Breguet overcoil (via base 1210) · flat in one lot
| Glucydur, Breguet overcoil
|-
|-
| regulator
| regulator
Line 740: Line 875:
|-
|-
| shock
| shock
| KIF-pattern
| "Rolex Shockresisting" device
|-
| date
| Non-quickset, dragging change
|}
|}


Cal. 1210 with a calendar added, the extra mechanism accounting for the jump from 4.27mm to 5.07mm in height. Rolex's plate for it makes the relationship literal: the sheet runs to two pages and lists nothing but the calendar parts — an enlargement ring, a date indicator seating, date discs, a set of screws and a date jumper screw — with everything else deferred to the 1210 plates. The date discs alone come in three finishes, champagne, silvered, and champagne printed in red and black, which is the sort of variation that survives on watches long after the paperwork is lost.
Cal. 1200 is the family's small-seconds variant and, at 3.65mm, its thinnest member. Moving the seconds from the centre to a subdial requires a separate main plate and train-wheel bridge rather than an added module. The plate, bridge, third and fourth wheels, pallet fork and staff are jewelled.
 
The bilingual parts plate specifies Rolex's own "Shockresisting" device rather than a trade name. It lists a pivoted Glucydur balance with roller and a regulated Glucydur balance with Breguet hairspring, the 18,000-vph oscillator inherited by the 1210 and 1215.
 
The caliber number is engraved in the balance-wheel hub sinking rather than on a bridge or the main plate. The same document directs watchmakers to Cal. 1210 for all shared parts, confirming the family's parentage.


The hairspring is the one point where the sources fight. By plate inheritance the 1215 takes the 1210's Breguet overcoil, since its own sheet specifies no balance; Antiquorum has catalogued a 1215 both ways, describing the movement in a ref. 9996 lot as having a "self-compensating flat balance spring, index regulator" and elsewhere giving the Breguet wording it uses for the 1210. That ref. 9996 entry is the only lot in the family to name a regulator type at all, and no lot anywhere describes any of these calibers as free-sprung.
No major-house lot names Cal. 1200, so its fitments remain unestablished. The high-beat small-seconds Cal. 1240 is better documented in the platinum Cellinium 5240 and 5241, with a monometallic balance adjusted to four positions and a flat hairspring. That caliber kept the architecture in production for about a decade after the Oysterdate ended.


The date is non-quickset and does not snap. The calendar wheel carries a pawl pin that comes round once in 24 hours and engages a tooth on a star wheel under the date disc, dragging it into place over roughly forty minutes before a jumper spring seats it — the same arrangement Rolex used through the 7xx, 1035 and 11xx calibers, with the instantaneous change arriving only with the 1065/1066 and the 15xx family. An owner reporting that the date starts creeping at 11.20 is describing correct behaviour, not a fault.
<span id="sport-vintage"></span>
== Vintage sport calibers (Submariner, GMT-Master, Explorer, Air-King) ==


Christie's brackets the changeover inside ref. 6494 tightly, cataloguing a circa-1956 example on Cal. 1210 and a circa-1958 example on Cal. 1215. Beyond the 6494 the caliber appears in the Speedking 6430, early 6694 production, and the 9996/9919. The claim that it also powered the first Oysterdates, refs. 6094 and 6294, is contradicted by the auction record: Antiquorum catalogues 6094 examples on Cal. 740 and a 6294 on Cal. 790, and 6294 lots carry an "adjusted to two positions, overcoil hairspring" formula this family never uses.
The A-series and Cal. 1030 preceded the long-running 15xx family. Cal. 1520 became its main uncertified movement, while Cals. 1560 and 1570 supplied chronometer-rated sport references into the 1980s.


<span id="cal-1216"></span>
<span id="cal-1030"></span>
=== Cal. 1216 ===
=== Cal. 1030 ===
{| class="wikitable" style="width:280px; font-size:90%;"
[[File:Cal 1030 movement.webp|thumb|right|220px|Cal. 1030, engraved "1030," 25 jewels, butterfly rotor]]
! detail
! value
|-
| type
| Manual (assumed, by family)
|-
| jewels
| not documented
|-
| status
| Number attested in the parts trade only
|}
 
Cal. 1216 is the family's genuine blank. It is often described as a 17-jewel variant of Cal. 1215, architecturally identical — a claim with no traceable source behind it, and one this page can no longer support.
 
What can be checked runs both ways. Against the caliber: Rolex's surviving parts-plate library covers 1200, 1210, 1215, 1220, 1225 and 1240 and skips 1216 entirely, and no lot at Antiquorum, Christie's, Sotheby's, Bonhams or Phillips describes a Rolex Cal. 1216. The one auction hit that looks right, a Heritage listing headed "Rolex Ref. 1216," is a case reference rather than a caliber. There is also a live collision to be careful of: Ronda's contemporaneous mechanical series ran 1211, 1213, 1215, 1216, 1217, 1218 and onward, so a Ronda 1216 sitting next to a Ronda 1215 is exactly the shape that manufactures a phantom Rolex sibling.
 
For the caliber: the watch-material trade carries it as a Rolex number. Cas-Ker's genuine-parts catalogue indexes Rolex 1216 between 1215 and 1220 in a list whose every other entry is a real Rolex caliber, and stocks a crown wheel screw under part number 1216.5420 — caliber-prefixed in Rolex's own numbering convention, which is not the kind of thing a supplier invents.
 
The honest reading is that Rolex designated a Cal. 1216 and that almost nothing about it has survived into the public record. Jewel count, seconds layout, beat rate and the references it went into are all unknown here, and anything stated about them elsewhere should be treated as inherited from the 1215 rather than observed.
 
<span id="cal-1220"></span>
=== Cal. 1220 ===
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 785: Line 899:
|-
|-
| type
| type
| Manual
| Automatic
|-
|-
| jewels
| jewels
| 18 (factory plate) · 17 (as signed)
| 25
|-
|-
| frequency
| frequency
| 21,600 vph (3 Hz)
| 18,000 vph (2.5 Hz)
|-
|-
| power reserve
| power reserve
| ~58h
| 42h
|-
|-
| size
| size
| 10½′′′ / Ø23.80mm × 4.27mm height
| 28.5mm × 5.85mm
|-
|-
| escapement
| escapement
Line 803: Line 917:
|-
|-
| balance
| balance
| Screwless, inertia blocks, flat hairspring
| Monometallic, blued Breguet spring
|-
| regulator
| Index with movable stud support
|-
|-
| shock
| shock
| KIF-pattern
| KIF
|}
|}


The Cal. 1210 platform run at a raised beat rate and rebuilt around a different oscillator. The beat-rate question that hung over this caliber is now closed from two directions in Rolex's own paperwork: the factory parts plate is headed "Train: 21.600," and the third edition of Rolex's ''Technical and Service Information'' (1978) lists "Caliber 1220 — 10½″ round — Manual-winding, 21,600 beat" in its table of current calibers. The stray 19,800 vph figure traces to a single machine-translated trade blog and is almost certainly contamination from the 1520, 1570 and 1600, which genuinely run at that rate.
Produced from 1950 to 1962, Cal. 1030 was Rolex's first bidirectional and fully in-house automatic. Its 5.85mm profile ended the domed Bubbleback caseback, while the cutaway "butterfly" rotor stamped ROLEX PERPETUAL PATENTED is its clearest visual identifier. Finishing includes perlage on the rhodium-plated main plate, brushed bridges, polished screw heads and red anodized-aluminium reversing wheels. A conventional index regulates the movement; the visible regulator arm distinguishes it from the later free-sprung 1560 and 1570. Documented fitments include ref. 6098 from 1952, Submariners 6536, 6536-1 and 6538, Explorer 6610 and Air-King 6552. The same movement appeared in chronometer and non-chronometer watches.


The oscillator is where the 21,600 generation parts company with the 18,000 one. Where the 1210 carries a screwed Glucydur balance with a Breguet overcoil, this generation runs a screwless smooth-rimmed balance with a flat hairspring, fine-timed by two inertia blocks set into the balance arms — supplied as a gilt and a nickel-plated pair, so the watchmaker can tell which is which at the bench. Rolex describes the same two-block arrangement on its 1520 and 1600, turned with a fine blade and good for roughly ten seconds a day across the full range of adjustment, with the index regulator handling anything larger. Horbiter reaches the same conclusion from the other end, describing the 1220 as the 1210 platform with the Breguet spring removed. The plate lists the regulator, stud support and regulating stud as discrete parts, which is what an index-regulated caliber looks like and what a free-sprung one does not.
<span id="cal-1035"></span>
 
=== Cal. 1035 ===
At auction the caliber is a near-ghost, appearing almost exclusively in the oversize ref. 8029, and the lots that do name it disagree with each other about dates. Phillips catalogued an 8029 as 1950 on Cal. 1220; Antiquorum gave case no. 714105 as circa 1951, also on Cal. 1220; Sotheby's catalogued that same case number as circa 1961 and declined to name a caliber. A 1950 date sits awkwardly with a high-beat caliber whose siblings are later-1960s work, and the record does not resolve it. The wider difficulty is that trade databases hold that 1220 movements are commonly signed 1225, which would push the caliber's real footprint — later-production Oyster Precision 6426 among them — under a number it does not wear. That signing claim could not be corroborated from an independent primary source and should be treated as unverified.
[[File:Cal 1035 movement.webp|thumb|right|220px|Cal. 1035, rotor engraved "Rolex Perpetual Patented" — EmmyWatch]]
 
<span id="cal-1225"></span>
=== Cal. 1225 ===
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 825: Line 933:
|-
|-
| type
| type
| Manual
| Automatic
|-
|-
| jewels
| jewels
| 17
| 25
|-
|-
| frequency
| frequency
| 21,600 vph (3 Hz)
| 18,000 vph (2.5 Hz)
|-
|-
| power reserve
| power reserve
| ~58h
| 42h
|-
|-
| size
| size
| 10½′′′ / Ø23.80mm × 5.07mm height
| 28.5mm &times; 6.66mm
|-
|-
| escapement
| escapement
Line 843: Line 951:
|-
|-
| balance
| balance
| Screwless, inertia blocks, flat hairspring
| Monometallic, temp + 5 positions
|-
|-
| regulator
| regulator
| Index with movable stud support
| Index (Cal. 1030 base)
|-
|-
| shock
| shock
| KIF
| Shock absorber
|-
| date
| Non-quickset, dragging change
|}
|}


Cal. 1220 with a calendar added, carrying later-production Oysterdate Precision 6694 through the family's final years, and by a wide margin the best-documented member of the group. Its factory plate reads Ø23.80mm, 5.07mm high, train 21,600, centre second, calendar, shock proof, 17 jewels, base calibre 1210, and lists the balance as part 7625, "Balance with flat hairspring, timed," alongside a gilt and a nickel-plated inertia block. Antiquorum's cataloguing agrees from outside the factory, giving "monometallic balance, shock absorber, self-compensating flat balance-spring" for a 1972 ref. 6426 and "self-compensating steel flat balance spring" for a 1966 ref. 6694. Several caliber databases print a Breguet overcoil for the 1225 instead; the factory plate and the auction record both say flat, and this page follows them. A Bonhams lot describing a 1225 with a "Gyromax balance" is a cataloguing slip — Gyromax is Patek Philippe's free-sprung system, and no Rolex caliber uses it.
Cal. 1035 adds a date to the 1030 and appeared in 1957. It powered Oyster Perpetual Date refs. 6518, 6530 and 6534, plus the Datejust Thunderbird 6609. Rolex describes its non-quickset calendar as "progressive": the date moves gradually through the night, unlike the instant-change 1036 GMT.


None of the Precision calibers on this page were chronometer-certified, which is why "Precision" rather than "Superlative Chronometer Officially Certified" appears on the dial across the whole line. Michael Stockton writing for Fratello, Giovanni Di Biase at Horbiter, and published bench teardowns all state it plainly. The designation is frequently misread as meaning hand-wound, which it does not — the automatic Air-King 5500 wore "Precision" on Cal. 1520 and "Super Precision" on Cal. 1530, neither of them certified either. Some 1225 movements are also stamped "UNADJUSTED," which is an import-duty declaration rather than a grade.
The 1035 inherits the 1030's conventional index regulator. Although auction descriptions do not name the regulator, the production dates and shared base support the index arrangement.


There is no hacking. Rolex's plate for the base 1210 lists the complete keyless works — setting lever and jumper, yoke and yoke spring, setting wheel, minute wheel, cannon pinion — with no stop lever or hack spring anywhere in it, and the 1978 service book carries hack-device chapters only for the late 1500 series and the 2030/2035.
Rolex stamped the 1035's self-winding bridge "1030," as it also did on the 1036. This causes auction catalogues to identify the same reference under both numbers. The calendar work and 6.66mm height distinguish the 1035 from the 5.85mm no-date 1030. A correct ref. 6534 contains a 1035 regardless of its bridge engraving.


The service picture is unusually well recorded for a caliber this cheap. Published teardowns put the recurring faults at the pendant tube and crown threads, the winding stem, the mainspring, and water damage to the date ring, and single out the early Oysterdate calendar construction as the weak piece of an otherwise strong movement — the same watchmaker who calls the date works improvable also describes the pallet fork as polished all over with the jewels lightly undercut, and rates the finishing a clear step above a standard ETA. The economics are the real constraint: genuine Rolex parts for these calibers now cost more than the watches, so a crown that lists at three figures gets replaced with a generic at a tenth of it, and independents charge a fraction of a factory service. Rolex's own service centres still take them on, and a 1974 example returned from a factory overhaul running two seconds a day with a measured 57-hour reserve.
<span id="cal-1530"></span>
 
=== Cal. 1530 ===
Auction lots put the caliber in refs 6426, 6466 and above all the 6694, from the later 1960s through to examples catalogued as late as 1979. A collector comparison of a 1966 6694 on Cal. 1215 against a 1973 one on Cal. 1225 places the changeover inside that reference around 1967.
[[File:Cal 1530 butterfly rotor.webp|thumb|right|220px|Cal. 1530-era butterfly rotor halves, Rolex coronet stamped]]
 
<span id="cal-1200"></span>
=== Cal. 1200 ===
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 872: Line 974:
|-
|-
| type
| type
| Manual
| Automatic
|-
|-
| jewels
| jewels
| 17
| 17 / 25 / 26 (market variants)
|-
|-
| frequency
| frequency
Line 881: Line 983:
|-
|-
| power reserve
| power reserve
| ~58h
| 44h
|-
|-
| size
| size
| 10½′′′ / Ø23.80mm × 3.65mm height
| 12½′′′
|-
|-
| escapement
| escapement
| Straight-line lever, jewelled pallet fork and staff
| Swiss lever, club-tooth
|-
|-
| balance
| balance
| Glucydur, Breguet overcoil
| Screwed Glucydur
|-
|-
| regulator
| regulator
| Index with movable stud support
| Index (coarse) + micro-star fine-adjust screws
|-
|-
| shock
| shock
| "Rolex Shockresisting" device
| KIF Flector
|}
|}


The small-seconds variant of the family and the thinnest of the group at 3.65mm, against 4.27mm for the sweep-seconds Cal. 1210 it is otherwise architecturally close to. Where the 1215 plate lists only its calendar parts, the 1200 gets its own main plate and its own train wheel bridge, because moving the seconds from the centre to a subdial rearranges the going train rather than adding to it. Its sheet lists a jewelled plate, jewelled train wheel bridge, centre wheel with cannon pinion, third and fourth wheels each with their own upper and lower jewels, and a jewelled pallet fork and staff, then closes by naming the nine Cal. 1210 parts the small-seconds layout does not need.
Cal. 1530 ran from 1957 to 1965. Its 17-, 25- and 26-jewel versions are concurrent market variants, not a chronological progression. Seventeen-jewel movements appear in a 1958-era ref. 5508, a 5500 and a 1011 Eaton, and Rolex's 1978 service booklet still treats low-jewel 1520 and 1530 movements as current configurations.
 
Cal. 1530 is the base for the 1520, 1560, 1570 and 1580. They share plates and many service parts, including interchangeable automatic-device bridges, so the engraved bridge number may not identify the movement beneath it. Balance-bridge and regulator form are more reliable. Cal. 1030, not 1530, was Rolex's first fully in-house automatic.
 
Regulation combines an index for coarse adjustment with two pairs of micro-star fine-adjustment screws on the outer balance rim. Turning a screw clockwise draws it inward and gains rate. The system resembles Microstella, and Horotec lists the same adjustment tool for the 1530 and later Microstella calibers, but Rolex reserved the Micro-Stella name for its free-sprung 12½-ligne chronometer movements. The 1530 retains an index.
 
The form-1 balance cock uses KIF Flector; forms 3 and 4 use Elastor, with form 2 also assigned to Flector by specialist comparisons. Interchangeable bridges mean an individual movement's shock setting may not match its engraved caliber number.


The original bilingual plate carries more of the family's mechanical detail than any other document found, because it states in Rolex's own words what the later English sheets only imply. It gives Ø23.8mm and 18,000 alternances, marks the movement with the "Rolex Shockresisting" device rather than a trade shock-protection brand, and names the balance twice: part 7535, a Glucydur balance with roller, pivoted, and part 7536, a Glucydur balance with Breguet hairspring, regulated. That is the 18,000-vph oscillator described by the manufacturer, and it is what the 1210 and 1215 inherit.
The hairspring remains disputed. Antiquorum consistently describes a Breguet overcoil and index regulator, while much of the reference literature gives a flat hairspring with stick regulation. Reliable sources support both descriptions.


The same plate answers a question the caliber databases argue over. The number is engraved on the hub sinking of the balance wheel — not on a bridge, not on the mainplate — which is why the balance appears among the 1200's special parts at all when the rest of the movement is shared with the 1210. It also carries the instruction that settles the family's parentage, directing the watchmaker to the plates of calibre 1210 for everything general.
Chronometer status also varies. Sotheby's describes the 1530 as uncertified, while Phillips and Christie's identify chronometer examples in the 5504 family. Rare 5512 and 5508 watches with four-line chronometer dials and Cal. 1530 have been reported, though no major-house lot confirms them. Certification appears to have been occasional. The Microstella-equipped 1555 and 1560 became the regular chronometer alternatives used in early refs. 1675 and 1016.


The gap worth stating: no auction lot at any major house was found naming Cal. 1200. Everything above comes from Rolex's own documentation rather than from catalogued watches, and the references this caliber went into are not established here. Its high-beat counterpart, the small-seconds Cal. 1240 built on the 1220, is far better attested — Sotheby's, Christie's and Antiquorum all catalogue it in the platinum Cellini Cellinium 5240 and 5241, describing a monometallic balance adjusted to four positions with a self-compensating flat balance spring, which is how this architecture kept running for a decade after the Oysterdate stopped.
The rotor changed from butterfly to half-moon during production. Later movements also gained blued automatic-bridge screws and coloured reversing wheels in place of brass-coloured gears. Rolex describes the red wheel finish as a hardening treatment for aluminium introduced in 1957; collector descriptions often call the wheels purple and Teflon-coated. Rotor and reversing-wheel form help date an example.


<span id="sport-vintage"></span>
The 1530 first entered the Submariner in ref. 5508, followed by 5510; neither was chronometer-rated at launch. It replaced the 10-series in non-chronometer watches, including Precision models, the Air-King, ref. 5504 "Super-Precision" Explorer and the Canadian Explorer-Date with Cal. 1535. Certified models such as the 6542 GMT, 6610 Explorer, Datejust and Day-Date retained 10xx calibers for longer. Strongly documented fitments include refs. 5508, 5510, 5512, 5513, 5500 and 5504. Single-lot support exists for 5501, 5502, 5506, 5516 and 5590/1011 Eaton. Bonhams listings for refs. 1002 and 1003 are internally inconsistent and remain unconfirmed.
== Vintage sport calibers (Submariner, GMT-Master, Explorer, Air-King) ==


The sport time-only and GMT line runs through three broad chapters: the A-series and Cal. 1030 opening generation above, a long 15xx-family middle chapter, and the GMT branch's own parallel thread through the bakelite-bezel era. The 15xx family anchors Rolex's longest-running production stretch — Cal. 1530 through the early 1960s, Cal. 1520 as its permanent non-chronometer twin, and Cal. 1560/1570 carrying the chronometer side of Submariner, GMT-Master, and Explorer production into the 1980s.
Rolex specifies a 0.122–0.125mm mainspring for the 18,000-vph 1530 and 1560, against up to 0.125 or 0.128mm for the higher-beat 1520 and 1570. Early unjewelled barrel-bridge arbor holes can wear; Rolex prescribed closing the hole or reaming it for a jewel, while later production received a bushing. Rotor-axle wear is another known fault. On the 1560, a hard shock could push the hairspring into the regulator. Rolex supplied a safety pin free of charge and later made it standard, so both guarded and unguarded examples are correct.


<span id="cal-1030"></span>
<span id="cal-1520"></span>
=== Cal. 1030 ===
=== Cal. 1520 ===
[[File:Cal 1030 movement.webp|thumb|right|220px|Cal. 1030, engraved "1030," 25 jewels, butterfly rotor]]
[[File:Cal 1520 movement.webp|thumb|right|220px|Cal. 1520, engraved "1520," EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 923: Line 1,030:
|-
|-
| jewels
| jewels
| 25
| 17 / 25 / 26
|-
|-
| frequency
| frequency
| 18,000 vph (2.5 Hz)
| 19,800 vph (2.8 Hz)
|-
| power reserve
| 42h
|-
|-
| size
| size
| 28.5mm × 5.85mm
| 12½′′′
|-
|-
| escapement
| escapement
Line 938: Line 1,042:
|-
|-
| balance
| balance
| Monometallic, blued Breguet spring
| Monometallic, screwless, flat hairspring
|-
| regulator
| Index (coarse) + two inertia blocks
|-
|-
| shock
| shock
Line 944: Line 1,051:
|}
|}


Rolex's first bidirectional automatic, 1950–62, 25 jewels, 18,000 vph, 42 hours, 28.5 × 5.85mm: the caliber that ends the domed-caseback era. Its "butterfly" rotor, named for its cutaway wing-like shape, is stamped ROLEX PERPETUAL PATENTED and is the single most recognizable identifier for the caliber. Straight-line lever escapement, monometallic balance adjusted to temperature and 5 positions, blued-steel self-compensating Breguet balance spring, KIF shock protection — confirmed across more than a half-dozen Antiquorum lot descriptions using near-identical wording every time. Perlage finishing on the rhodium-plated mainplate, brushed (not striped) bridges, polished screw heads, and red anodized-aluminum reversing wheels round out the finishing. Regulation runs on a traditional index rather than free-sprung Microstella, so a visible regulator arm near the balance is the fastest way to tell a 1030 apart from its free-sprung 1560/1570 successors at a glance — the free-sprung system wasn't patented until 1957, which rules it out here on dating grounds alone. It first appears on the 6098 in 1952, running through the 6536, 6536-1, and 6538 Submariners, the 6610 Explorer, and the 6552 Air-King, in both COSC and non-COSC form on the identical movement. It was Rolex's first fully in-house automatic, no external ébauche supplier, with a 5.85mm profile thin enough to leave the bubble-caseback era behind for good.
Produced from 1963 to 1990, Cal. 1520 is the non-chronometer, higher-beat derivative of the 1530. Rolex pairs the 18,000-vph 1530 with the 1560, and the 19,800-vph 1520 with its certified counterpart, the 1570.
 
Rolex describes regulation by an index and two inertia blocks, one gilt and one nickel-plated, on a screwless balance with a flat hairspring. Turning their splits inward slows the movement and outward gains rate, with about ten seconds per day across the adjustment range. The index handles coarse changes. This differs from both the 1530's micro-star screws and the 1570's free-sprung Microstella system.
 
Certified calibers use free-sprung Microstella regulation; Cal. 1520 uses an index and inertia blocks.
 
The rim weights can be mistaken for a free-sprung system, but factory documentation confirms the regulator and inertia blocks. Two Bonhams descriptions call the 1520's balance "free-sprung Gyromax," an error that applies Patek Philippe's trademark to an index-regulated Rolex movement.
 
Auction descriptions consistently give a flat hairspring, apart from one 2013 Antiquorum outlier that says Breguet. Shock protection is KIF in Flector or Elastor form, identified by balance-bridge and regulator shape. That shape is more reliable than the engraved caliber number because bridges interchange across the series.
 
The 17-, 25- and 26-jewel counts are concurrent market variants. The 17-jewel version uses a different main plate and bridges, altered escape-wheel pivot geometry, and bushings in place of jewels in the automatic module. The going train and balance are unchanged, so jewel count does not affect timekeeping. Dated examples place 17- and 26-jewel movements together from the mid-1960s, with 25-jewel examples running alongside them.
 
American tariffs rose sharply above 17 jewels, but Rolex did not document this as the reason for the low-jewel version. Seventeen-jewel movements also reached Europe and Asia, so general cost reduction remains another possibility. The American presentation ref. 7002 has a rotor marked "SEVENTEEN JEWELS" and "UN" for unadjusted, both relevant to the tariff schedule, but this does not settle the question.
 
Documented fitments include the 5513, 5514 COMEX, 5517 military Submariner, 5500 Air-King and 5520. Ref. 1002 uses chronometer calibers 1530 or 1570; apparent 1520 examples are ref. 5500 cases with 1002 stamped inside the caseback. Ref. 5501 remains unconfirmed. Hacking arrived as a running change around 1972 through parts 8073 and 8074. Two lines above six o'clock identify the non-chronometer dial, against four on certified models.
 
The barrel bridge and arbor hole are known wear points. Rolex prescribed closing a worn hole or reaming it for a 2.30mm jewel; a later beryllium bushing largely solved the problem. Rotor axles and autowinder wheels also wear, and replacement parts are scarce. Gritty manual winding is normal because the reversers run without lubrication.


<span id="cal-1035"></span>
<span id="cal-1535"></span>
=== Cal. 1035 ===
=== Cal. 1535 ===
[[File:Cal 1535 movement.webp|thumb|right|220px|Cal. 1535, EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 956: Line 1,080:
|-
|-
| jewels
| jewels
| 25
| 26
|-
|-
| frequency
| frequency
Line 965: Line 1,089:
|-
|-
| size
| size
| 28.5mm &times; 6.66mm
| 28.5mm
|-
|-
| escapement
| escapement
| Straight-line lever
| Swiss lever
|-
|-
| balance
| balance
| Monometallic, temp + 5 positions
| Monometallic, screwed
|-
|-
| regulator
| regulator
| Index (Cal. 1030 base)
| Index, pre-Microstella
|-
|-
| shock
| shock
| Shock absorber
| Shock-absorber
|}
|}


The date version of Cal. 1030, from 1957, powering the Oyster Perpetual Date 6518, 6530, and 6534 and the Datejust Thunderbird 6609. Non-quickset &mdash; Rolex's own service documentation describes its calendar mechanism as "progressive," meaning the date creeps forward gradually through the night rather than jumping instantaneously at midnight, deliberately contrasted against the 1036 GMT caliber's instant-change wording in the same table.
Cal. 1535 is the non-chronometer date version of the 1530, introduced in 1957 for the Air-King-Date 5700/5701. Rolex's factory caliber table places it before the later 1520-based Cal. 1525, consistent with the production dates. Monochrome likewise assigns both calibers to the 5700, with 1535 first.
 
Auction houses usually catalogue refs. 5700 and 5701 under the base caliber. Antiquorum assigns a 1963 ref. 5700 to Cal. 1530 and a 1972 example to 1520, though neither base movement has a date. Those entries agree with Rolex's grouping of 1535 components under Cal. 1530 and 1525 components under Cal. 1520, but they do not identify the fitted caliber.


Antiquorum's description of a 6534 sold in Geneva in November 2008 gives the mechanical spread in full: rhodium-plated, 25 jewels, straight-line lever escapement, monometallic balance adjusted to temperatures and 5 positions, shock absorber, self-compensating Breguet balance spring. A second Geneva lot from March 2008 for the same reference repeats it word for word. Neither names the regulator, and no 1035-specific description does; the Cal. 1030 base it inherits is documented with a traditional index rather than free-sprung Microstella, which is also the only reading compatible with the dates, since Rolex did not patent the free-sprung system until 1957.
No auction lot identifies a Cal. 1535 directly, so the listed mechanical figures come from its Cal. 1530 base. Evidence for the hairspring conflicts: auction wording gives a flat spring, while Rolex balance assembly 7855 for the 1530 uses a Breguet overcoil. Repeated catalogue boilerplate is more likely than a separate variant. The 1535 predates Microstella and uses an index with a screwed balance, consistent with the 5700's Precision grade.


The identification problem with this caliber is genuinely awkward, and Rolex created it. The factory table records that the 1035's self-winding bridge is stamped "1030" &mdash; the movement carries its parent's number, not its own, exactly as the 1036 does. The consequence shows up immediately in the auction record: lots for a single reference come up catalogued both ways, and the 6534 in particular has been sold as a Cal. 1030 watch by one house and a Cal. 1035 watch by another, with Christie's cataloguing a 6534 under Cal. 1030 as recently as May 2024. Reading the number off the bridge cannot resolve which one is in the case. What can is the calendar work itself and the height: 6.66mm for the 1035 against 5.85mm for the plain 1030, a 0.81mm difference accounted for entirely by the date mechanism stacked on top. A 6534 is a Date reference, so the movement in a correct example is a 1035 whatever the bridge says.
Although Cal. 1530 was phased out by 1965, its 1535 date derivative remained in the Air-King-Date into the late 1980s.


<span id="cal-1530"></span>
<span id="cal-1525"></span>
=== Cal. 1530 ===
=== Cal. 1525 ===
[[File:Cal 1530 butterfly rotor.webp|thumb|right|220px|Cal. 1530-era butterfly rotor halves, Rolex coronet stamped]]
[[File:Cal 1525 movement.webp|thumb|right|220px|Cal. 1525, EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 997: Line 1,123:
|-
|-
| jewels
| jewels
| 17 / 25 / 26 (market variants)
| 17 / 25
|-
|-
| frequency
| frequency
| 18,000 vph (2.5 Hz)
| 19,800 vph (2.8 Hz)
|-
|-
| power reserve
| power reserve
| 44h
| 42h
|-
|-
| size
| size
| 12½′′′
| 28.5mm
|-
|-
| escapement
| escapement
| Swiss lever, club-tooth
| Swiss lever
|-
|-
| balance
| balance
| Screwed Glucydur
| Monometallic, flat hairspring
|-
|-
| regulator
| regulator
| Index (coarse) + micro-star fine-adjust screws
| Index
|-
|-
| shock
| shock
| KIF Flector
| Shock-absorber
|}
|}


1957–65, 18,000 vph, 44 hours, club-tooth Swiss lever escapement, screwed Glucydur balance. The 17-, 25- and 26-jewel counts are market variants available across the run rather than a progression: 17-jewel examples are confirmed in catalogue text on a 1958-era 5508, a 5500 and a 1011 Eaton, and Rolex's own 1978 service booklet still discusses 17-jewel 1520–1530 models as a live configuration two decades later.
Cal. 1525 is the higher-beat, non-chronometer date version of the 1520. Introduced in 1965, it carried the Air-King-Date 5700/5701 through later production. Contemporary chronometer-rated Oyster Perpetual Date references used a related 1500-series caliber instead.


The 1530 is the root of the whole 15-series. Rolex derived the 1520, 1560, 1570 and 1580 from it; they share base plates and a great many parts, and the caliber number engraved on the automatic-device bridge interchanges freely across the range, so a bridge stamped 1555 on a movement that is physically something else proves nothing about the watch. What separates them is the shape of the balance bridge and regulator. That interchangeability, and the durability that came with it, is the 1530's real contribution. It was not Rolex's first automatic, a distinction that belongs to the Cal. 1030 of 1950 and gets misassigned to the 1530 often enough to be worth stating.
Auction catalogues often label the date-equipped Cal. 1525 as Cal. 1520. Antiquorum does so on a 1972 ref. 5700, while describing the expected flat hairspring and index-regulated architecture. The chronometer-grade 1560 and 1570 use a Breguet overcoil and Microstella. The Cal. 1525 uses the index regulation associated with the uncertified 5700.


Regulating it is a two-stage job. An index regulator handles coarse rate, and the balance also carries two pairs of adjustable micro-star fine-timing screws on the rim; on the 1530 and its immediate derivatives those screws sit on the outside, where turning one clockwise tightens it inward and the watch gains, while the later 3135-generation balances put the equivalent nuts on the inner rim. The Swiss tool-maker Horotec lists the same micro-star tool for the 1530 alongside the 1570, 2130, 3035, 3055, 3135 and 3155, which is good evidence the screws are a real feature and not a misreading. Rolex's own literature reserves the Micro-Stella name for the 12½′′′ chronometer calibers of 18,000 and 19,800 beat, describing those as carrying eighteen balance screws of which two are the gold star-headed regulating pair, so the 1530's screws work on the same principle without belonging to the system Rolex named. That is the ambiguity long-standing Vintage Rolex Forum contributors circle around when they compare a 1530 balance against a 1675 or 1016 and find stick regulation and a Microstella-like adjuster on the same wheel.
Jewel counts of 17, 25 and 26 reflect parallel market executions. Rolex balance-assembly numbers confirm a flat hairspring for the 1520 and 1525, against a Breguet spring on the 1530 and Microstella on the 1560. The 1525 remains index-regulated.


Shock protection is KIF Flector on the form-1 balance cock, per a named UK specialist who maps cock forms 1 and 2 to Flector and forms 3 and 4 to Elastor, with two watchmakers on the NAWCC board reaching the same reading by physically comparing cocks. The caveat matters as much as the answer: because caliber-marked bridges interchange across the entire 15-series, an individual example's shock setting can differ from what its stamped number implies. That is the reason secondary sources disagree about it, rather than any of them being simply wrong.
<span id="cal-1560"></span>
 
=== Cal. 1560 ===
There is a genuine unresolved contradiction over the escapement and regulating description, and it runs between source tiers rather than within one. Antiquorum's standard formula for the 1530 reads "straight-line lever escapement, monometallic balance, shock absorber, self-compensating Breguet balance spring, index regulator," giving it an overcoil; much of the reference literature instead describes a flat hairspring with stick regulation. Both readings are in circulation from sources that are otherwise reliable, and nothing in the record resolves it.
[[File:Cal 1560 movement.webp|thumb|right|220px|Cal. 1560, EmmyWatch]]
 
Chronometer status is murkier still, and the tidy version does not survive contact with the sources. Three major houses disagree outright: Sotheby's catalogues the 1530 as not chronometer-certified, while Phillips and Christie's both describe it as the chronometer caliber used in 5504-family watches. Collector research adds a third position, documenting rare four-line Superlative Chronometer dials on 5512 and 5508 examples running a 1530 — though no major-house lot confirms one, which makes it the weakest strand here. The safest reading is that certification was occasional rather than either routine or impossible. What is documented is the shape of Rolex's answer rather than the reason for the gap: the 1555 and 1560 were the chronometer upgrade, easier to bring to tolerance because of the Micro-Stella balance, which is why the earliest 1675 and 1016 carry them. Explanations that a cost calculation drove the omission trace to a single forum contributor who labelled the idea his own speculation, and they are not carried here.
 
The rotor shape evolves mid-production from butterfly to half-moon, and continental auction houses name it directly, cataloguing early examples as a "rotor papillon" or "masse papillon." Later runs add blued screws on the auto-winding bridge — Rolex's own strip-down instructions open by calling for "the three blue screws of the automatic bridge" — with coloured reversing wheels replacing the original brass-coloured gears. Collectors describe those wheels as purple and Teflon-coated; Rolex describes the red finish as a surface treatment applied to aluminium for hardness and dates its introduction to 1957, the 1530's own first year. Either way, both are genuine dating markers for a given example.
 
First Submariner appearance is the 5508, with the 5510 following months later, and neither was chronometer-rated at launch. The wider pattern is that the 1530 came in as the replacement for the 10-series in Rolex's non-chronometer watches — the 6536 becomes the 5508, the 6538 becomes the 5510 — arriving alongside new Precision models, the Air-King, the 5504 "Super-Precision" Explorer and the Canadian-market Explorer-Date with its Cal. 1535. It did not immediately displace the older calibers where certification mattered: the 6542 GMT, the 6610 Explorer, and the Datejust and Day-Date lines all held onto their 10xx movements for a while yet. Multi-house lots confirm the 1530 in the 5508, 5510, 5512, 5513, 5500 and 5504, with thinner single-lot support for the 5501, 5502, 5506, 5516 and the 5590/1011 Eaton. Two Bonhams online-tier lots catalogue a 1002 and a 1003 as Cal. 1530 against the Watch-Wiki concordance that assigns it to the 5500 family only, but both carry internal inconsistencies and no other house corroborates them — a shaky outlier rather than a confirmed fitment.
 
Three service details are worth carrying, all of them factory-documented. Rolex specifies mainspring strength of 0.122 to 0.125mm for the 18,000-beat 1530 and 1560, against up to 0.125 or 0.128mm for the 19,800-beat 1520 and 1570, which is worth knowing on any movement rebuilt with whatever was on the bench. The unjewelled barrel bridge and arbor hole wear in early production, and Rolex's instructions cover both closing the hole and reaming it for a jewel; later production got a bushing that largely ended it, and rotor-axle wear on the winding weight is the companion complaint. And the family's known defect sits one caliber over: hard jarring could throw a 1560's hairspring out far enough to catch the regulator, which Rolex fixed with a safety pin supplied free of charge from its Material Division and made standard partway through production, so some carry it and some do not. The factory booklet devotes a page to those hairspring guards, which is about as clear an admission of a recurring fault as Rolex ever put in print.
 
<span id="cal-1520"></span>
=== Cal. 1520 ===
[[File:Cal 1520 movement.webp|thumb|right|220px|Cal. 1520, engraved "1520," EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,050: Line 1,164:
|-
|-
| jewels
| jewels
| 17 / 25 / 26
| 26 (25 in some lot descriptions)
|-
|-
| frequency
| frequency
| 19,800 vph (2.8 Hz)
| 18,000 vph (2.5 Hz)
|-
|-
| size
| power reserve
| 12½′′′
| 42h (secondary sources only)
|-
|-
| escapement
| escapement
Line 1,062: Line 1,176:
|-
|-
| balance
| balance
| Monometallic, screwless, flat hairspring
| Free-sprung monometallic, Microstella screws
|-
| regulator
| Index (coarse) + two inertia blocks
|-
|-
| shock
| shock
| KIF
| KIF (pattern not named in lots)
|}
|}


1963–90, 17/25/26 jewels at 19,800 vph, the non-chronometer member of the higher-beat pair. Rolex's own factory parts plate heads the caliber "Base Calibre 1530," which is the accurate lineage: the 1520 is a 1530 derivative that took over at the faster rate. The pairing worth remembering is by beat, not by name. Rolex's service literature sets 1530 against 1560 at 18,000 vph and 1520 against 1570 at 19,800 vph, so the 1520's certified counterpart is the 1570, not the 1530 it descends from.
Cal. 1560 arrived in 1959 as the chronometer-grade 15xx movement, with a free-sprung balance adjusted to temperature and five positions. Auction catalogues give both 25 and 26 jewels without establishing a pattern. Antiquorum usually describes a Breguet overcoil; its flat-hairspring description for one ref. 1502/1503 is an outlier.


That same literature is unusually direct about how the thing is regulated. The factory booklet lists it as "12½′′′ round, self-winding, 19,800 beat, regulation by regulator and inertia blocks," and sets it against the Cal. 1570 on the same page, regulated "by Micro-Stella systems." The 1520's balance is screwless and its hairspring flat; two inertia blocks, one gilt and one nickel (parts 8056-1 and 8056-2), sit on the balance rim and are turned with a hairspring-collet blade. Directing their splits toward the centre of the wheel slows the watch and turning them outward gains time, with roughly ten seconds a day of correction available from one extreme to the other. Coarse rate comes from the regulator. Note that this is not the 1530's arrangement: that caliber trims with micro-star screws, and the two systems are often conflated.
Cal. 1560 uses free-sprung Microstella regulation; Cal. 1530 uses an index. Watches made from 1959 to 1965 were tested by the Bureaux Officiels de Contrôle de la Marche des Montres, usually under collective certificates and to a standard around −1/+10 seconds per day in five positions. COSC did not exist until September 1973, so describing an early 1560 as COSC-certified is anachronistic.


What actually sorts the certified calibers from the uncertified ones across this family is the regulating system, not the hairspring. Rolex states that Micro-Stella is used in all 12½′′′ Rolex chronometers of 18,000 and 19,800 beat, and describes the 1520's screwless balance, flat hairspring, regulator and inertia blocks as the alternative arrangement. The flat hairspring is well documented — seven independent Antiquorum lot descriptions carry it — but it did not by itself keep the caliber out of certification, since the 1530 has a Breguet overcoil and went mostly uncertified too. Free-sprung Micro-Stella regulation is what correlates.
Factory balance 7980 is used in the 18,000-vph chronometer group: 1555, 1556, 1560 and 1565. Later replacement part 8106 and balance bridge 8102 span both 18,000- and 19,800-vph family members, so a serviced 1560 may carry the later balance. Documented fitments include the four-line 5512, 5504 and Explorer 1016. The GMT-Master 1675 instead used the 1565 to about the 1.4-million serial range and the 1575 thereafter. Family-wide bridge engravings explain 1675 movements marked 1560 or 1570; a base 1560 lacks both calendar and 24-hour works. Although 1570 became the new fitment in 1965, 1560 movements appear in Explorers until about 1967.


The arrangement gets misread constantly, because eccentric weights on a balance rim look like a free-sprung system. Watchmakers on the NAWCC message board have argued in circles over whether a 1520 even has a regulator, one contributor concluding after comparing examples that they turn up "some with regulators, some without, some with the eccentric weights, some without, but none with the microstella screws." The auction record repeats the confusion in a more damaging form: two Bonhams lots describe a 26-jewel 1520 as having a "free-sprung Gyromax balance," a Patek Philippe trademark attached to a movement that is neither free-sprung nor Patek's.
<span id="cal-1565"></span>
 
=== Cal. 1565 ===
Antiquorum's house wording is the dependable one and it holds across lots spanning twenty years: "straight-line lever escapement, monometallic balance, shock-absorber, self-compensating flat balance-spring." One Antiquorum lot from 2013 says "Breguet" where every other lot from the same house says flat, and it reads as boilerplate slippage. Shock protection is real but never named in a catalogue; houses write "shock-absorber" or "antichoc" and stop. A specialist repairer's identification guide covering the 1520 to 1580 range attributes the series to KIF in Flector and Elastor patterns, assigned by which of four balance-bridge-and-regulator forms a movement carries, and makes the useful point that the bridge shape rather than the caliber number engraved on it is what identifies these movements, since the numbered bridge interchanges across the whole series.
[[File:Cal 1565 movement.webp|thumb|right|220px|Cal. 1565, EmmyWatch]]
 
{| class="wikitable" style="width:280px; font-size:90%;"
The 17-, 25- and 26-jewel counts are market variants, not a chronology, and the jewels are not where people assume. Rolex's own parts numbering shows the 17-jewel version using a different main plate, different bridges, different escape-wheel pivot geometry and bushings in place of jewels in the automatic module — so it is a physically different movement, but the differences are confined to the winding module and escape wheel and never touch the going train or the balance, which is why jewel count has no bearing on timekeeping. Dated lots put 17-jewel movements between 1965 and 1970 and 26-jewel movements inside that same window and earlier: a 26-jewel 5513 at case 1'293'711 sits about 22,000 serials from the 17-jewel Sealab III 5513. A 25-jewel tier runs alongside both, on a 9ct 5500 with a 1967 London import mark and a 1973 Pan Am 5500.
 
The tariff explanation deserves care in both directions. The bracket itself is real and citable: the Tariff Schedules of the United States broke sharply above 17 jewels, taxing higher-count movements at a steep premium over the low-jewel rate. Whether that specifically drove Rolex's choice is undocumented, and the best forum research argues against the simple reading — one long-standing contributor reports 17-jewel movements going to Europe and Asia as well as the United States, and reads the change as general cost-cutting from the mid-1960s rather than US-market targeting. No auction catalogue states a reason at all. The American corporate-presentation reference 7002 does carry a 1520 rotor stamped "SEVENTEEN JEWELS" and "UN" for unadjusted, the two declarations the US schedules keyed on, which is suggestive without settling it.
 
Fitment is better documented than for most vintage calibers, and one common attribution is wrong. Major-house lots confirm the 1520 in the 5513 across case numbers from roughly 1.29 million to 8.46 million, in the 5514 COMEX, in the 5517 military Submariner, in the 5500 Air-King and in the 5520, the last unusually well, since the same 1983 watch, case 7'473'941, was catalogued as a 26-jewel 1520 by Antiquorum in 2006 and again by Christie's in 2008. The 1002 Oyster Perpetual does not belong on that list: every apparent "1002 with a 1520" turns out to be a 5500 case with 1002 stamped inside the caseback, while lots for an actual 1002 run chronometer calibers, 1530 or 1570. The 5501 sits in the same doubtful column, appearing with a 1520 in dealer listings but not in any major-house lot. Hacking arrives as a running change around 1972, via parts 8073 and 8074 and the factory section on the hack device for late 1500-series movements, and it dates an example usefully. There is also a dial tell for the non-chronometer status: a 1520 watch carries two lines of text above six o'clock rather than the four a chronometer-certified movement earns, a point Sotheby's makes explicitly, and Phillips describes early 5513s as carrying the 1530 and later ones the "non-chronometer cal. 1520."
 
On service, Rolex's instructions for the series single out the barrel bridge and barrel arbor hole as the wear point, with directions for closing a worn hole or reaming it to take a 2.30mm jewel; later production got a beryllium bushing that largely ended the problem. Rotor-axle wear is the other documented item, and independent watchmakers add worn autowinder wheels, with the difficulty that Rolex no longer supplies parts. One symptom that is not a fault: gritty or grainy manual winding is normal on a 1520, because the reversers are designed to run unlubricated.
 
<span id="cal-1535"></span>
=== Cal. 1535 ===
[[File:Cal 1535 movement.webp|thumb|right|220px|Cal. 1535, EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
! value
! value
Line 1,100: Line 1,199:
|-
|-
| jewels
| jewels
| 26
| 25–26 (sources disagree)
|-
|-
| frequency
| frequency
Line 1,106: Line 1,205:
|-
|-
| power reserve
| power reserve
| 42h
| 44h
|-
| size
| 28.5mm
|-
|-
| escapement
| escapement
| Swiss lever
| Straight-line lever
|-
|-
| balance
| balance
| Monometallic, screwed
| Free-sprung, Microstella
|-
| regulator
| Index, pre-Microstella
|-
|-
| shock
| shock
| Shock-absorber
| KIF
|}
|}


A date-module variant of Cal. 1530, from 1957, non-chronometer, powering the 5700/5701 Air-King-Date. That attribution rests on two things, neither of them an auction catalogue. Rolex's own factory caliber table, in Mark Sirianni's transcription, places 1535 as the earlier, 1530-based date module and 1525 as the later, 1520-based one below — a reading the dates themselves require, since a movement derived from Cal. 1520 cannot predate 1520's own 1963 introduction. Editorial coverage of the line agrees: Erik Slaven's history of the Air-King for Monochrome, January 2025, gives the 5700 calibre 1535 with some examples on 1525, both Precision grade rather than chronometer.
Produced from 1959 to 1965, Cal. 1565 is the early ref. 1675's "caller" GMT movement: its 24-hour hand remains linked to the main hour hand rather than independently adjustable. Rolex kept that layout until Cal. 3085. The 1565 introduced a free-sprung Breguet overcoil with Microstella regulation to this lineage, replacing the index used by earlier sport calibers.


No auction lot names this caliber. Across Antiquorum, Sotheby's, Phillips and Bonhams, the 5700 and 5701 lots that should carry a 1535 are catalogued under the base caliber instead — Antiquorum gave a 1963 Explorer-Date 5700 as Cal. 1530, in Revolution: The Evolution of the Rolex Sport Watch, New York, 17 April 2008, lot 93, and a 1972 example of the same reference as Cal. 1520, in New York on 11 December 2008, lot 71. Neither reading works literally, because neither base caliber carries any date work at all. Taken as house shorthand for the family rather than the exact variant, the two lots line up with the order the factory table gives: earlier watch on the earlier base, later watch on the later base. Rolex's parts catalogues group the date variants the same way, filing 1535 components against the 1530 and 1525 against the 1520. That is corroboration of the lineage, not confirmation of the caliber number, and the distinction is worth holding onto.
<span id="cal-1570"></span>
 
=== Cal. 1570 ===
Every mechanical figure in the table above is read across from the 1530 base rather than observed on a movement catalogued as a 1535. Those 1530 lot descriptions give rhodium plating, 26 jewels, straight-line lever escapement, monometallic balance, self-compensating flat balance spring. The flat spring cuts against the parts evidence. Rolex balance assembly 7855, the one specified for the 1530, carries a Breguet overcoil; the flat spring belongs to assembly 8055 and the 1520. Both readings sit in the record, and boilerplate is the likelier explanation than a variant, since the same house prints near-identical movement wording across the whole 1500 family. What is not in dispute is that the 1530 predates Microstella. Rolex introduced those screws on the 1565 in 1959, two years into 1530 production, so a 1535 regulates at an index against a screwed balance — the arrangement Rolex found too slow to certify at volume, which is much of why the 5700 was sold as a Precision rather than a chronometer.
[[File:Cal 1570 movement.webp|thumb|right|220px|Cal. 1570, open caseback]]
 
Cal. 1530 is the root of the whole 1500 family, in production from 1957 and phased out by 1965 as the 1560, 1570 and 1520 divided the range between them at different price points. The 1535 outlived its own base by decades inside the 5700, which is how a late-1980s Air-King-Date ends up carrying a movement whose design predates the Submariner's crown guards.
 
<span id="cal-1525"></span>
=== Cal. 1525 ===
[[File:Cal 1525 movement.webp|thumb|right|220px|Cal. 1525, EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,143: Line 1,230:
|-
|-
| jewels
| jewels
| 17 / 25
| 26
|-
|-
| frequency
| frequency
Line 1,149: Line 1,236:
|-
|-
| power reserve
| power reserve
| 42h
| 48h
|-
|-
| size
| size
| 28.5mm
| 12.5′′′ (28.2mm)
|-
|-
| escapement
| escapement
| Swiss lever
| Straight-line lever
|-
|-
| balance
| balance
| Monometallic, flat hairspring
| Free-sprung monometallic, four Microstella screws
|-
| regulator
| Index
|-
|-
| shock
| shock
| Shock-absorber
| KIF (Flector or Elastor)
|}
|}


A date-module variant of Cal. 1520, from 1965, non-chronometer, carrying the 5700/5701 Air-King-Date through its later production years — the higher-beat 19,800 vph sibling of Cal. 1535 above. The chronometer-rated date option in this generation runs on a related 1500-series caliber instead, in the 1500/1501/1503/1505 Oyster Perpetual Date.
Cal. 1570 is the 19,800-vph revision of the 1560, introduced in 1965. It retains the free-sprung Breguet overcoil and Microstella regulation, with adjustment to temperature and five positions. Family-wide bridge engraving causes date movements such as the 1575 in a ref. 1665 to appear marked 1570; the engraving alone does not identify the exact caliber.
 
The balance has four Microstella screws in two opposing pairs, not two. Rolex required equal adjustment within each pair to preserve poise. The larger pair changes rate by about two seconds per day and the smaller by about one. On this family the screws sit in the balance rim; the later 3135 platform moves its Microstella nuts to the inner rim.


Antiquorum catalogued a 5700 Explorer-Date made in 1972 as Cal. 1520 rather than 1525 — rhodium-plated, 26 jewels, straight-line lever escapement, monometallic balance, shock absorber, self-compensating flat balance spring, in New York on 11 December 2008, lot 71. That base-caliber habit runs through the house's 5700 lots, and it is why the auction record is a poor place to go looking for the number 1525 itself: the date function is a module, and the catalogue describes the movement underneath it. What the record does establish is the architecture, and it is the cost-controlled end of the 1500 family. The flat balance spring is the tell. The chronometer-grade members of the same generation, the 1560 and 1570, carry a Breguet overcoil, and the absence of one here is the mechanical reason a 5700 dial reads Precision rather than Superlative Chronometer.
KIF's circa-1972 material catalogue lists Flector and Elastor settings for Rolex; it does not list Ultraflex. Auction catalogues name only a shock absorber, while Rolex part 8065 serves the upper balance setting across the 1520, 1530, 1560 and 1570. The available records support Flector and Elastor.


Jewel counts move around in the record — 17 and 25 in caliber listings, 26 in the Antiquorum lot descriptions — which is normal for a movement built in parallel executions for different markets and not evidence of a variant. The regulating system is settled by Rolex's own balance-assembly part numbers. The 1520 takes assembly 8055 with a flat hairspring, against 7855 with a Breguet spring on the 1530 and 7980 with Microstella screws on the 1560. Microstella entered the 1500 family with the 1565 in 1959 and never reached the 1520 or the 1525, so rate on this pair is set at an index rather than on the balance rim.
Hacking appeared gradually around 1971–72, with timing varying by model. Cal. 3035 began replacing the 1570 in new production from 1977, but the Explorer 1016 retained it until 1988–89. The documented diameter is 12.5 lignes, or 28.2mm; the often-published 28.5mm is a rounded conversion. Published heights conflict.


<span id="cal-1560"></span>
<span id="cal-1575"></span>
=== Cal. 1560 ===
=== Cal. 1575 ===
[[File:Cal 1560 movement.webp|thumb|right|220px|Cal. 1560, EmmyWatch]]
[[File:Cal 1575 movement.webp|thumb|right|220px|Cal. 1575, EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,184: Line 1,270:
|-
|-
| jewels
| jewels
| 26
| 26 (25 per Ashton Tracy)
|-
|-
| frequency
| frequency
| 18,000 vph (2.5 Hz)
| 19,800 vph (2.8 Hz)
|-
|-
| power reserve
| power reserve
| 42h
| 48h
|-
|-
| escapement
| escapement
| Swiss lever
| Straight-line lever
|-
|-
| balance
| balance
| Free-sprung, Microstella
| Free-sprung monometallic, Microstella screws (1570 balance)
|-
|-
| shock
| shock
| KIF Flector
| KIF (Flector or Elastor)
|}
|}


1959–65, 26 jewels, 18,000 vph, 42 hours, the cross-family chronometer bridging Cal. 1530 and Cal. 1570 architecturally. It gains jewels over the 1530 and, like the 1570 after it, carries COSC certification, without yet reaching the 1570's higher 19,800 vph beat rate. The balance assembly is Rolex part number 7980: Microstella regulation screws, a free-sprung Breguet overcoil hairspring, and KIF Flector shock protection, the same balance package the 1570 inherits unchanged. Powers mid-production 5512, 1675, and 1016.
Cal. 1575 adds calendar work to the 1570; the GMT execution also adds a 24-hour train. Antiquorum and Sotheby's give 26 jewels, while watchmaker Ashton Tracy's 2018 ''Quill & Pad'' study gives 25. Tracy records a 48-hour power reserve; the often-published 50-hour figure lacks support.
 
Rolex engraved the 1575 bridge "1570," so that marking on a ref. 1680 or 1675 identifies the caliber family. Factory parts records distinguish 1565G, 1575, 1575G and 1575GMT. Date and GMT versions are separately catalogued builds, and the GMT parts also circulated as a conversion set for a standard 1560 or 1570.
 
The 1575 shares factory balance assembly 8106 with the 1570 and related family members. It has shock protection on the escape wheel on both dial and movement sides, as well as on the balance. Documented fitments include the Submariner 1680, GMT-Master 1675 from about the 1.4-million serial range, Explorer II 1655 and Sea-Dweller 1665.


<span id="cal-1565"></span>
<span id="gmt-branch"></span>
=== Cal. 1565 ===
== GMT-Master line ==
[[File:Cal 1565 movement.webp|thumb|right|220px|Cal. 1565, EmmyWatch]]
 
Early GMT calibers synchronized both hour hands. Cal. 1036 and 1065 belong to the bakelite-bezel 6542 era. Cal. 1565, 1575, and 3075 retained that "caller" layout through the 1675 and 16750 generations. Cal. 3085 introduced an independently adjustable local-hour hand, while Cal. 3175 retained the synchronized layout in the 16700 until 1999 alongside the Cal. 3185 and 3186 used in the 16710.
 
<span id="cal-1036"></span>
=== Cal. 1036 ===
[[File:Cal 1036 movement.webp|thumb|right|220px|Cal. 1036, EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,215: Line 1,310:
|-
|-
| jewels
| jewels
| 25–26 (sources disagree)
| 25
|-
|-
| frequency
| frequency
Line 1,221: Line 1,316:
|-
|-
| power reserve
| power reserve
| 44h
| 42h (secondary sources only)
|-
|-
| escapement
| escapement
| Straight-line lever
| Straight-line lever (inferred, 1030 base)
|-
|-
| balance
| balance
| Free-sprung, Microstella
| Monometallic (inferred, 1030 base)
|-
|-
| shock
| shock
| KIF
| KIF (inferred)
|}
|}


1959–65, 25 or 26 jewels depending on source, 18,000 vph, 44 hours, the "caller" GMT caliber in the early 1675 — 24-hour hand still linked to the main hour hand rather than jumping independently, the layout the whole GMT branch carries until Cal. 3085 breaks the pattern decades later. Antiquorum's own cataloguing of a 1675 names it directly and marks the regulating-organ transition this caliber represents: monometallic balance, KIF shock protection, and — for the first time in this lineage — a free-sprung self-compensating Breguet spring with Microstella regulating screws in place of the index regulator every earlier sport caliber on this page uses, consistent with Rolex's free-sprung system reaching production only after its 1957 patent.
Cal. 1036 is Rolex's first GMT movement, a Cal. 1030 with a 24-hour train added for the bakelite-bezel 6542. It runs at 18,000 vph and was chronometer certified. The 6542 used Cal. 1036 first, followed by 1065 and 1066 during its 1955&ndash;1959 production run. Its period chronometer certificate came from the Bureaux Officiels; COSC did not exist until 1973.
 
The start year remains disputed. Phillips dates the 6542's release to 1954, Hodinkee starts production in 1955, and Rolex registered the GMT-Master name on 21 April 1955. An announcement in 1954 followed by sales in 1955 would reconcile those dates, but Rolex has not documented that sequence.
 
The listed escapement, balance and shock protection are inferred from the Cal. 1030 base; no Cal. 1036 source documents them directly. Auction catalogues seldom identify a 6542 movement as Cal. 1036, so those three specifications remain provisional.


<span id="cal-1570"></span>
<span id="cal-1065"></span>
=== Cal. 1570 ===
=== Cal. 1065 ===
[[File:Cal 1570 movement.webp|thumb|right|220px|Cal. 1570, open caseback]]
[[File:Cal 1065 movement.webp|thumb|right|220px|Cal. 1065, EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,246: Line 1,345:
|-
|-
| jewels
| jewels
| 26
| 25
|-
|-
| frequency
| frequency
| 19,800 vph (2.8 Hz)
| 18,000 vph (2.5 Hz)
|-
|-
| power reserve
| power reserve
| 44h
| 42h (secondary sources only)
|-
| size
| 28.5mm × 5.75mm
|-
|-
| escapement
| escapement
| Swiss lever
| Straight-line lever (inferred, 1030 base)
|-
|-
| balance
| balance
| Free-sprung, 2 Microstella screws
| Monometallic (inferred, 1030 base)
|-
|-
| shock
| shock
| Kif Ultraflex
| KIF (inferred)
|}
|}


1965–80, 26 jewels, 19,800 vph, 44 hours, 28.5 × 5.75mm — the higher-beat successor to Cal. 1560, with hacking added mid-life. Free-sprung Breguet hairspring with screw-based poising, two Microstella screws for regulation, Kif Ultraflex shock protection. It runs across the Submariner and Explorer lines through the late 1970s, and dealer listings that describe a "1500" as carrying Cal. 1575 are often describing a 1570 instead — the movement resolves the confusion, not the dial text.
Cal. 1065 is the mid-run 6542 caliber. Multiple Phillips lots identify it as an automatic movement with 25 jewels, the same jewel count recorded for the Cal. 1066 that followed.
 
Its dates are less secure than its specification. Cal. 1065 sits second in the 6542's three-movement sequence and is generally dated to 1957, but no factory document or dated lot fixes the transition. The 42-hour power reserve is also a secondary-source figure.
 
The escapement, balance, and shock rows likewise derive from the Cal. 1030 base. Cal. 1066 cataloguing supports that family relationship, but these details have not been documented directly on a Cal. 1065.


<span id="cal-1575"></span>
<span id="cal-1066"></span>
=== Cal. 1575 ===
=== Cal. 1066 ===
[[File:Cal 1575 movement.webp|thumb|right|220px|Cal. 1575, EmmyWatch]]
[[File:Cal 1066 movement.webp|thumb|right|220px|Cal. 1066, stamped "1066," butterfly rotor engraved "Rolex Perpetual Patented," EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,283: Line 1,383:
|-
|-
| frequency
| frequency
| 19,800 vph (2.8 Hz)
| 18,000 vph (2.5 Hz)
|-
|-
| power reserve
| power reserve
| 50h
| 42h
|-
| balance
| Free-sprung (inherits 1570 balance)
|-
| shock
| Kif Ultraflex
|}
|}


1965–80, 25 jewels, 19,800 vph, 50 hours — adds either a date module or a GMT module onto the 1570 base, which is how the same caliber number lands on the 1680 (date), the late 1675 (GMT), and the 1655 Explorer II (GMT with 24-hour bezel) simultaneously.
Cal. 1066 was the third and final movement fitted to the 6542, replacing Cal. 1065 for the last two years of production. It runs at 18,000 vph with 25 jewels and about 42 hours of reserve. Antiquorum describes a straight-line lever escapement, monometallic balance adjusted to temperature and five positions, shock absorber, and self-compensating Breguet hairspring. Its matching descriptions for Cal. 1030 and 1065 support a shared base with GMT work added.


<span id="gmt-branch"></span>
The regulator and balance specification remain uncertain. Cal. 1030 descriptions name an index regulator, while Cal. 1066 descriptions omit it; one 6542 is catalogued with a free-sprung Glucydur balance. This may mark a running change or inconsistent cataloguing. A circa-1959 Phillips example directly confirms the Cal. 1066's butterfly rotor.
== GMT-Master line ==


The GMT branch reads in three distinct steps rather than a single continuous upgrade path. Cal. 1036 and 1065 belong to the bakelite-bezel 6542 era and keep the 24-hour hand synchronized to the main hour hand. Cal. 1565, 1575, and 3075 carry that same synchronized "caller" layout through the 1675 and 16750 generation. Cal. 3085 then breaks the pattern with the GMT branch's first independently jumping local hour hand, and Cal. 3175 keeps the older synchronized layout alive in parallel on the 16700 until 1999 even as Cal. 3185 and 3186 define the long 16710 run that follows.
Documented examples cluster in 1958 and 1959, including a steel 6542 with a IV.1958 caseback and two gold watches dated to 1959. Rolex changed caliber numbers during the reference's run, so two outwardly similar 6542s can carry different movements.


<span id="cal-1036"></span>
<span id="cal-3075"></span>
=== Cal. 1036 ===
=== Cal. 3075 ===
[[File:Cal 1036 movement.webp|thumb|right|220px|Cal. 1036, EmmyWatch]]
[[File:Cal 3075 movement.webp|thumb|right|220px|Cal. 3075, engraved "3075," EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,313: Line 1,406:
|-
|-
| jewels
| jewels
| 25
| 27
|-
|-
| frequency
| frequency
| 18,000 vph (2.5 Hz)
| 28,800 vph (4 Hz)
|-
|-
| power reserve
| power reserve
| 42h
| 48h
|-
|-
| escapement
| escapement
| Straight-line lever (inferred, 1030 base)
| Straight-line lever
|-
| balance
| Free-sprung monometallic, Microstella screws
|-
| balance support
| Balance cock (3035 generation)
|-
|-
| shock
| shock
| KIF (inferred)
| KIF (inferred; lots record only "shock absorber")
|}
|}


1954–59, 25 jewels, 18,000 vph, 42 hours — the first GMT caliber, in the bakelite-bezel 6542. Rotor and bridge spell out "TWENTY FIVE JEWELS" in full rather than abbreviating it, an early-production engraving convention that helps date a given example.
Cal. 3075 carried the synchronized "caller" GMT layout into the 16750 generation. It has 27 jewels, a straight-line lever escapement, a monometallic balance adjusted to temperature and five positions, a free-sprung Breguet hairspring regulated by Microstella screws, hacking, and quickset. The quickset advances only the date wheel.
 
The balance is monometallic, not Glucydur. Catalogue descriptions identify Microstella screws but do not record their count, material, or position on the rim. They also name a shock absorber without identifying its maker, so the KIF attribution remains inferred from Rolex practice of the period.
 
The 3075 belongs to the 3035 generation and uses its cantilevered balance cock. Cal. 3175 and 3185 later introduced a balance bridge anchored at both ends. Its start date is disputed: the 16750 did not appear in a Rolex catalogue until 1981, while Antiquorum dates production of the 16758 to 1979. Known fitments are the steel 16750, steel-and-gold 16753, and gold 16758. The 3075 also moved the GMT hand above the hour hand, reversing the Cal. 1575 stack; later GMT calibers retained that arrangement.


<span id="cal-1065"></span>
<span id="cal-3085"></span>
=== Cal. 1065 ===
=== Cal. 3085 ===
[[File:Cal 1065 movement.webp|thumb|right|220px|Cal. 1065, EmmyWatch]]
[[File:Cal 3085 movement.webp|thumb|right|220px|Cal. 3085, EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,341: Line 1,444:
|-
|-
| jewels
| jewels
| 25
| 27
|-
|-
| frequency
| frequency
| 18,000 vph (2.5 Hz)
| 28,800 vph (4 Hz)
|-
|-
| power reserve
| power reserve
| 42h
| 48h
|-
| size
| 28.5mm × 6.3&ndash;7.2mm (sources disagree)
|-
|-
| escapement
| escapement
| Straight-line lever (inferred, 1030 base)
| Swiss lever
|-
| balance
| Free-sprung, Microstella
|-
|-
| shock
| shock
| KIF (inferred)
| KIF (per published specs, unconfirmed)
|}
|}


1956–59, 25 jewels, 18,000 vph, 42 hours, the mid-6542 GMT caliber succeeding Cal. 1036 within the same bakelite-bezel generation.
Cal. 3085 ran from 1983 to 1989 on the Cal. 3035 platform, with 27 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, and chronometer certification. It was the first Rolex caliber to separate the local-hour hand from the 24-hour hand. The crown jumps the local hour forward or backward in one-hour steps without disturbing the minutes, seconds, or home-time hand. The date advances only by cycling the local-hour hand, so the movement has no direct quickset date.
 
Published thickness figures conflict. Grail Watch Reference gives 6.3mm, while Caliber Corner gives 7.2mm against the Cal. 3185's 6.45mm. The 16760's thick movement and case produced the "Fat Lady" and "Sophia Loren" nicknames. Cal. 3085 appeared only in the 16760 GMT-Master II and 16550 Explorer II. Published specifications agree on a Breguet hairspring and Microstella regulation, but KIF shock protection has not been confirmed by an auction description or Rolex document.


<span id="cal-1066"></span>
<span id="cal-3175"></span>
=== Cal. 1066 ===
=== Cal. 3175 ===
[[File:Cal 3175 movement.webp|thumb|right|220px|Cal. 3175, EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,368: Line 1,480:
|-
|-
| jewels
| jewels
| 25
| 31
|-
|-
| frequency
| frequency
| 18,000 vph (2.5 Hz)
| 28,800 vph (4 Hz)
|-
|-
| power reserve
| power reserve
| 42h
| 48h
|-
| escapement
| Swiss lever
|-
| balance
| Free-sprung Glucydur, Microstella
|-
| balance support
| Balance bridge (3135 generation)
|-
| shock
| KIF Elastor (3100-family text, not lot-confirmed)
|}
|}


1957–59, 25 jewels, 18,000 vph, 42 hours — the third and final movement Rolex fitted to the 6542 across its five-year run, replacing Cal. 1065 for the last two years of production. All three 6542 calibers (1036, 1065, 1066) share the base 1030 architecture with a GMT module added — same straight-line lever escapement, monometallic balance, blued Breguet spring, index regulator, KIF shock protection, confirmed directly for the 1066 across three separate Antiquorum lots using word-for-word the 1030 formula; the inheritance for 1036 and 1065 specifically is not independently attested and should be read as inferred rather than observed. The GMT module adds roughly 0.18mm of height over the plain 1030 and changes nothing in the regulating organ. Rolex changed the caliber number with each running revision rather than keeping one number through the reference's life, which is why an early and a late 6542 can carry different movements despite looking identical from the dial side.
Cal. 3175 ran from 1988 to 1999 with 31 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, quickset, and chronometer certification. Auction descriptions confirm the jewel count and adjustment to temperature and five positions. Published 3100-family specifications support a free-sprung Glucydur balance, Microstella regulation, Breguet hairspring and KIF Elastor setting. No examined Cal. 3175 lot confirms KIF Elastor.
 
Architecturally, Cal. 3175 is a Cal. 3135 with a fixed 24-hour hand. It uses the 3135's balance bridge, anchored at both ends, where Cal. 3075 used a cantilevered cock. The 24-hour hand remains linked to the local hour hand, so a second time zone is read from the rotating bezel. The 16700 kept this synchronized layout while the rest of the line moved to the jumping-hour Cal. 3185.
 
Cal. 3175 appeared only in the 16700 and was Rolex's last fixed GMT movement. Reports of factory Cal. 3185 fitment in late 16700s rest on a contradictory parts listing and a rebuilt watch; documented Cal. 3185 fitment belongs to the 16710. Sotheby's has incorrectly described Cal. 3175 as having an independent GMT hand. The accepted 16700 production span is 1988&ndash;1999, although Fratello gives 2001 in one account. The 1997 change from tritium to Super-LumiNova affected the dial, not the movement.


<span id="cal-3075"></span>
<span id="cal-3185"></span>
=== Cal. 3075 ===
=== Cal. 3185 ===
[[File:Cal 3075 movement.webp|thumb|right|220px|Cal. 3075, engraved "3075," EmmyWatch]]
[[File:Cal 3185 movement.webp|thumb|right|220px|Cal. 3185, engraved "3185"]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,390: Line 1,518:
|-
|-
| jewels
| jewels
| 27
| 31
|-
|-
| frequency
| frequency
Line 1,398: Line 1,526:
| 48h
| 48h
|-
|-
| escapement
| size
| Swiss lever
| 6.45mm
|-
|-
| balance
| balance
| Free-sprung, four Microstella screws
| Free-sprung Glucydur, four Microstella nuts
|-
| shock
| KIF
|}
|}


1979–88, 27 jewels, 28,800 vph, 48 hours, hacking, quickset, chronometer — carries the synchronized "caller" GMT layout into the 16750/16753/16758 generation. Free-sprung balance with four gold Microstella screws on the inner rim, Breguet overcoil, Swiss lever escapement, KIF shock protection at both balance jewel stations — the same regulating organ as Cal. 3035, carried on a balance cock rather than a bridge.
Cal. 3185 ran from 1989 to about 2007. Derived from Cal. 3135 with added 24-hour work, it has 31 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, quickset, chronometer certification, and KIF Elastor shock protection. It powered the 16710, 16713, 16718, and 16570, replacing Cal. 3085 in the GMT-Master II and Explorer II.
 
The balance carries four Microstella nuts arranged as two opposing pairs of different sizes. Rolex's Microstella wrench instructions require equal adjustment of both nuts in a pair to preserve the balance-wheel poise. Adjusting one without its opposite puts the wheel out of poise.
 
At 6.45mm, Cal. 3185 is slimmer than the Cal. 3085 it replaced, allowing the 16710 to sit flatter than the "Fat Lady" 16760. Its practical identification tell is visible during setting: the 24-hour hand twitches slightly as the local hour jumps. Cal. 3186 removed that play, so the test distinguishes the two without opening the case.


<span id="cal-3085"></span>
<span id="cal-3186"></span>
=== Cal. 3085 ===
=== Cal. 3186 ===
[[File:Cal 3085 movement.webp|thumb|right|220px|Cal. 3085, EmmyWatch]]
[[File:Cal 3186 movement.webp|thumb|right|220px|Cal. 3186, engraved "3186"]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,421: Line 1,550:
|-
|-
| jewels
| jewels
| 27
| 31
|-
|-
| frequency
| frequency
Line 1,427: Line 1,556:
|-
|-
| power reserve
| power reserve
| 48h
| 50h
|-
|-
| size
| size
| 28.5mm × 6.3&ndash;7.2mm (sources disagree)
| 28.5mm &times; 6.45mm
|-
|-
| escapement
| escapement
Line 1,436: Line 1,565:
|-
|-
| balance
| balance
| Free-sprung, Microstella
| Monometallic, free-sprung
|-
| regulator
| Microstella screws, no index
|-
|-
| shock
| shock
| KIF (inferred)
| Shock-absorber, pre-Paraflex
|}
|}


1983–89, 27 jewels, 28,800 vph, 48 hours, hacking, chronometer. The first Rolex caliber to dissociate the local-hour hand from the 24-hour hand: with the crown in its second (one-click-out) position, turning it jumps the local hour hand forward or backward in full one-hour steps — snapping cleanly to each hour rather than sweeping through the minutes — while the minute and seconds hands, and the 24-hour "home time" hand, stay completely undisturbed. A traveler resets local time without touching the hand tracking home. The cost is quickset date, which now advances only via the local-hour hand. The 6.3mm figure widely quoted for its case-driving thickness is contradicted by Rolex's own parts diagram, which gives 7.20mm — either way the movement's thickness drove the 16760 "Fat Lady" / "Sophia Loren" case proportions, and it ran exclusively in the 16760 GMT-Master II and the 16550 Explorer II.
Cal. 3186 ran from 2007 to 2019. It added a Parachrom hairspring to the Cal. 3185 base while retaining 31 jewels, a 28,800 vph frequency, hacking, quickset, and chronometer certification; reserve increased to 50 hours. It powered late 16710 production and the ceramic-bezel 116710LN, 116710BLNR, and 116719BLRO.
 
The movement has a straight-line lever escapement, monometallic balance adjusted to temperature and five positions, shock protection, a free-sprung Breguet-form hairspring, Microstella regulation, and hacking. One Antiquorum description calls the hairspring blued steel, but Cal. 3186 uses Parachrom, a niobium-zirconium alloy coloured by an oxide layer rather than tempering.
 
Cal. 3186 retains the Cal. 3135 architecture used by the 3185: 28.5mm diameter, 6.45mm height, 28,800 vph, and 31 jewels. It also keeps the plain-bearing oscillating-weight axle, part 568, shared with Cal. 3130, 3135, 3155, and 3175. Once lubricant migrates, the axle wears and requires replacement and riveting at service.
 
Rolex introduced Cal. 3186 as a running change, leaving its start date unsettled. Steel 16710 examples begin among late Z- and M-series cases; the lowest documented example is Z 5786xx, but higher Z-series watches can still contain Cal. 3185. Gold references changed earlier. A D-series 116718 catalogued with Cal. 3186 was sold in August 2006, placing the movement in production before the commonly cited 2007 steel transition.
 
Both Cal. 3185 and 3186 index the local-hour hand with a jumping-hour click. Cal. 3186 reworked the parts and reduced slack between the drive-train wheels. On Cal. 3185, the 24-hour hand twitches when the local hour jumps; on Cal. 3186, it remains still. The test identifies the caliber without opening the case.


<span id="cal-3130"></span>
The jumping-hour click spring is the caliber's known failure point. A failed spring lets the local-hour hand glide instead of indexing in one-hour steps and can leave it loose on its wheel. Rolex superseded part 657 first with 657-1 and then 657-2; the later springs are stronger and slightly larger. The fault is documented across the 16710, 16570, 116710, 116713, 116718, and 116719, as well as Cal. 3187. It usually leaves other components undamaged. The hour-jump action should be checked on an unserviced watch.
=== Cal. 3130 ===
 
[[File:Cal 3130 movement.webp|thumb|right|220px|Cal. 3130, engraved "3130," EmmyWatch]]
<span id="cal-3187"></span>
=== Cal. 3187 ===
[[File:Cal 3187 movement.webp|thumb|right|220px|Cal. 3187, official Rolex photo, engraved "3187," blue Parachrom hairspring, free-sprung Microstella balance]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,461: Line 1,603:
|-
|-
| power reserve
| power reserve
| 48h
| 48–50h (sources disagree)
|-
|-
| size
| size
| 28.5mm &times; 5.85mm
| 30.97mm (contested; 28.5mm also published)
|-
|-
| escapement
| escapement
Line 1,470: Line 1,612:
|-
|-
| balance
| balance
| Monometallic Glucydur, free-sprung
| Monometallic, free-sprung
|-
|-
| regulator
| regulator
Line 1,476: Line 1,618:
|-
|-
| shock
| shock
| KIF Elastor
| Paraflex
|}
|}


c.1999–2018, 31 jewels, 28,800 vph, 48 hours, hacking, chronometer — the time-only successor to Cal. 3000, carrying the 14060M, 114060, 114270, and 114200 through the 2000s and 2010s. The upgrade over the 3000 is a full balance bridge in place of a partial one, a larger balance wheel, and a Breguet overcoil hairspring. Calling it a date-less Cal. 3135 is not an analogy: Rolex's own parts sheet for the caliber prints "Base Calibre 3135" beneath a specification block reading Ø28.50mm, Ht 5.85mm, Train 28.800, 31 jewels. The start of the run is softer than the end — 1999, 2000 and 2001 all appear in print for the introduction, and no Rolex document has surfaced to settle it.
Cal. 3187 is an enlarged Cal. 3186, widened to move the date window outward in the 42mm Explorer II case. It powered only the 216570 from 2011 to 2021, before Cal. 3285 replaced it in the 226570. The Parachrom hairspring, Breguet overcoil, and independently adjustable local-hour hand carry over from the GMT lineage. Paraflex is new here, replacing the KIF Elastor used by Cal. 3185 and making Cal. 3187 the first movement in this family with Rolex's own shock system.
 
Cal. 3187 uses a larger baseplate and reworked surrounding parts but retains the Cal. 3186 regulating organ: a straight-line lever escapement, free-sprung monometallic balance under a full bridge, and Microstella regulation without an index. Auction catalogues confirm 31 jewels but do not itemize those inherited components.
 
Rolex launched the 216570 and Cal. 3187 together in March 2011 for the Explorer II's fortieth anniversary. The 42mm case required the larger movement, while the orange 24-hour hand recalled the 1655. Both remained in production until 2021, and no other reference used the caliber.
 
Two documented unit commissions use Cal. 3187. A 2012 white-dial 216570 made for members of the British Special Air Service carries "Who Dares Wins," the winged-dagger badge, and its owner's identifiers. A circa-2015 example numbered 40/48 was made for the UK Attack Helicopter Force. These were unit commissions rather than ministry-issued watches and should not be classified with the 5513 MilSub.


That bridge is the substantive change. Cal. 3000 hung its balance from a cock anchored on one side only; the 3130 spans the balance with a bridge screwed down at both ends, which holds endshake stable under lateral shock and makes the larger, heavier balance wheel worth fitting in the first place. Antiquorum prints the rest of the regulating organ in full on the lots it has handled: rhodium-plated, straight-line lever escapement, monometallic balance adjusted to temperatures and five positions, shock absorber, self-compensating free-sprung Breguet balance spring, Microstella regulating screws, hack mechanism, in the wording used for a PVD-coated 14060M in New York on 10 March 2010, lot 164. Free-sprung is the load-bearing word. There is no regulator index on this movement; rate is set by turning the Microstella nuts on the Glucydur balance rim to move mass inward or outward and change the wheel's inertia. That is slower work on the bench than sliding an index, and it is why a 3130 holds its rate through a knock that would push a regulated movement out of tolerance. Shock protection is KIF Elastor rather than Rolex's own Paraflex, the single component that separates a 3130 from the Cal. 3132 that replaced it and the fastest way to place an open movement in the right decade. The height is worth getting right, because secondary listings routinely hand the 3130 the 3135's 6.00mm on the reasoning that the two are otherwise identical. Rolex's sheet has it 0.15mm thinner at 5.85mm, and that 0.15mm is the date mechanism the 3130 does without. The main plate is its own casting too, part 3130-100 rather than a reused 3135 item, though small pieces such as the screw for the dial distance piece still carry 3135 numbers.
Cal. 3187 inherited the 3186's jumping-hour click-spring failure. On affected watches, the local-hour hand glides instead of indexing in one-hour steps. Rolex revised the part twice, and serviced examples may carry the later, stronger spring.


The caliber's odd distinction is that it spent its first years uncertified. The 14060M carried it from launch under a two-line dial with no chronometer designation, Rolex having declined to send the no-date Submariner's movements through COSC while certifying the same architecture in the Submariner Date alongside it. Certification came in late 2007 and the dial gained two more lines reading Superlative Chronometer Officially Certified. Nothing inside changed. The market has since inverted the logic and pays a premium for the two-liner, which makes the 3130 one of the few Rolex movements whose paperwork is worth less than its absence.
The &minus;2/+2 rating applies only after Rolex redefined Superlative Chronometer in 2015. Earlier watches carried the COSC &minus;4/+6 seconds-per-day standard for the uncased movement; later examples were tested again by Rolex as complete watches. The underlying caliber did not change beyond regulation.


The known wear point sits in the automatic work rather than the escapement. The 3130 shares its oscillating-weight axle, Rolex part 568, with the 3135, 3155, 3175 and 3185, and that axle runs in a plain sleeve bearing rather than a ball race — fine while the oil holds, steadily worn once it migrates. A rotor that has developed play works a fine reddish dust through the movement, and replacing and riveting the axle is a routine bench job at service rather than a fault report. Sotheby's has sold the caliber in an Explorer 114270 of circa 2002 under the shortest description the house uses, cal. 3130 automatic, 31 jewels, which is roughly how the market treats it: a movement nobody argues about.
<span id="sport-modern"></span>
== Modern sport calibers (1988–2020) ==


One derivative is worth knowing about. Cal. 3131, announced in 2007, is the 3130 rebuilt for magnetic resistance: blue Parachrom hairspring, a paramagnetic escape wheel in nickel-phosphorus alloy, and a two-part soft-iron shield closed around the movement inside the case. It went into the Milgauss 116400 and 116400GV and later the Air-King 116900, which makes the 3130 the base of two quite different watches — an unremarkable no-date Submariner movement on one hand, and Rolex's answer to a thousand-gauss field on the other.
Cal. 3000 introduced a 28,800-vph no-date movement, followed by Cals. 3130 and 3132. Cal. 3135 powered three decades of Submariner Date production.


<span id="cal-3132"></span>
<span id="cal-3000"></span>
=== Cal. 3132 ===
=== Cal. 3000 ===
[[File:Cal 3132 movement.webp|thumb|right|220px|Cal. 3132]]
[[File:Cal 3000 movement.webp|thumb|right|220px|Cal. 3000]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,500: Line 1,649:
|-
|-
| jewels
| jewels
| 31
| 27
|-
|-
| frequency
| frequency
Line 1,506: Line 1,655:
|-
|-
| power reserve
| power reserve
| 48h
| 42h (48h in some sources)
|-
|-
| size
| size
| 30.97mm (contested; 28.5mm also published)
| 28.5mm × 5.8mm
|-
| escapement
| Swiss lever
|-
|-
| balance
| balance
| Monometallic Glucydur, free-sprung
| Adjustable-mass, flat hairspring
|-
| regulator
| Microstella screws, no index
|-
| shock
| Paraflex
|}
|}


2010–c.2020, 31 jewels, 28,800 vph, 48 hours, hacking, chronometer — Cal. 3130 with a Parachrom hairspring and Paraflex shock system added, powering the 214270 Explorer.
Cal. 3000 is the no-date member of the 3000 family, used from about 1990 to 2001 in the Air-King 14000 and 14010, Submariner 14060, and Explorer 14270. The often-quoted 1988 start belongs to Cal. 3135. The Air-King changed to reference 14000M in 2000, while the Explorer became the 114270 and the Submariner adopted Cal. 3130 in 2001. Published power-reserve figures conflict at 42 and 48 hours; no Rolex figure settles the difference.


The base architecture is untouched: straight-line lever escapement, free-sprung monometallic Glucydur balance under a full bridge, Microstella regulating screws, no index. Bonhams catalogues it in the compressed form the house prefers — 31-jewel Cal. 3132 automatic, adjusted to temperature and 5 positions — for a DLC-coated 214270 carrying a cloisonné enamel world-map dial, sold at New Bond Street on 15 December 2021 as lot 54. What changed sits at either end of the balance staff. Paraflex replaced the KIF Elastor settings the 3130 used; Rolex's published figure for the gain is up to fifty per cent better shock resistance, from a spring geometry modelled in three dimensions so the setting cannot deform or unseat on impact. Parachrom replaced the Nivarox-type hairspring, a niobium-zirconium alloy that is paramagnetic by composition and blue by a surface oxide treatment Rolex patented separately from the alloy itself.
Cal. 3000 was Rolex's last movement without a Breguet overcoil. It uses a flat hairspring, unlike the outgoing 1570 generation and the rest of the 3000 family. Microstella adjustment sets the rate without an index, the hairspring is glued to the balance stud, and shock protection is KIF. COSC certification used the standard &minus;4/+6 seconds-per-day tolerance.


The 3132 matters more for what it marks than for what it does. Parachrom had been in Rolex movements since Cal. 4130 arrived in the 2000 Daytona, but the 214270 is where both Parachrom and Paraflex reach the time-only professional line, and the Submariner waited until Cal. 3230 in 2020 for either. For a decade the Explorer carried a technically newer regulating organ than the Submariner sitting beside it in the same catalogue, an inversion of the usual order that has quietly become one of the 214270's better arguments.
<span id="cal-3035"></span>
 
=== Cal. 3035 ===
Both dial generations of the 214270 run the same caliber. The 2010 launch dial has short Mercedes hands and solid white-gold 3, 6 and 9 numerals with the luminous filling left out; the 2016 revision lengthens the hands and fills the numerals. Neither change reaches the movement, so the price gap between the two dials is entirely a dial argument. The 3132 also inherits the 3130's automatic work, including the plain-bearing oscillating-weight axle that wears once its lubricant migrates.
[[File:Cal 3035 movement.webp|thumb|right|220px|Cal. 3035, engraved "3035," EmmyWatch]]
 
The caliber's run also straddles a change in what its certification meant. Rolex redefined Superlative Chronometer in 2015, moving the guaranteed figure from COSC's &minus;4/+6 seconds a day on the bare movement to &minus;2/+2 on the cased watch, tested a second time in Rolex's own laboratories and backed by the green seal and a five-year international guarantee. A 214270 delivered in 2012 and one delivered in 2018 carry identical movements under different promises, which matters when a seller quotes a rate figure from the wrong side of that line.
 
<span id="cal-3175"></span>
=== Cal. 3175 ===
[[File:Cal 3175 movement.webp|thumb|right|220px|Cal. 3175, EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,545: Line 1,679:
|-
|-
| jewels
| jewels
| 31
| 27
|-
|-
| frequency
| frequency
Line 1,552: Line 1,686:
| power reserve
| power reserve
| 48h
| 48h
|-
| balance
| Free-sprung, four Microstella screws
|-
| shock
| KIF Elastor
|}
|}


1988–99, 31 jewels, 28,800 vph, 48 hours, hacking, quickset, chronometer, adjusted to 5 positions and temperature, Glucydur balance with Microstella, Breguet hairspring, Kif shock. The last "caller" GMT and the last fixed-GMT caliber Rolex built, running in a single reference, the 16700 — the 24-hour hand stays linked to local hour, and the second time zone reads off the bezel rather than an independent hand, keeping the older synchronized layout alive right up to 1999 even as the rest of the GMT line had already moved on to the jumping-hour Cal. 3185.
Cal. 3035 ran from 1977 to 1988 in the 16800, 168000, 16808, and 16803. It was the first quickset Submariner caliber, with 27 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, and chronometer certification. Compared with the Cal. 1570 generation, it increased frequency from 19,800 vph and added a crown position that advances the date wheel directly. Its free-sprung Nivarox Breguet overcoil is regulated by four Microstella screws and protected by KIF Elastor.
 
Two construction details separate it from Cal. 3135. Its balance sits on a cantilevered cock, and its hairspring is glued to the stud. Cal. 3135 uses a bridge anchored at both ends and a laser-welded hairspring stud.


<span id="cal-3185"></span>
<span id="cal-3130"></span>
=== Cal. 3185 ===
=== Cal. 3130 ===
[[File:Cal 3185 movement.webp|thumb|right|220px|Cal. 3185, engraved "3185"]]
[[File:Cal 3130 movement.webp|thumb|right|220px|Cal. 3130, engraved "3130," EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,576: Line 1,718:
|-
|-
| size
| size
| 6.45mm
| 28.5mm &times; 5.85mm
|-
| escapement
| Swiss lever
|-
|-
| balance
| balance
| Free-sprung, two Microstella nuts
| Monometallic Glucydur, free-sprung
|-
| regulator
| Microstella screws, no index
|-
| shock
| KIF Elastor
|}
|}


1989–c.2007, 31 jewels, 28,800 vph, 48 hours, hacking, quickset, chronometer, KIF Elastor shock. Derived directly from the Cal. 3135 platform with an added 24-hour GMT hand mechanism, powering the 16710, 16713, 16718, and 16570. Both Microstella nuts are always adjusted identically as a pair, a documented service note to avoid poise imbalance. At 6.45mm it's noticeably slimmer than the 7.2mm Cal. 3085 it replaced, part of why the 16710 case reads thinner on the wrist than the earlier "Fat Lady" 16760.
Cal. 3130 is the time-only successor to Cal. 3000, used in the 14060M, 114060, 114270, and 114200. It brought a full balance bridge, a larger balance wheel, and a Breguet overcoil hairspring. Rolex's parts sheet identifies Cal. 3135 as the base and gives 28.5mm diameter, 5.85mm height, 28,800 vph, and 31 jewels. Published introduction dates range from 1999 to 2001; the precise year remains unsettled.
 
Cal. 3000 supports its balance from a cock anchored on one side; the 3130 uses a bridge secured at both ends, which stabilizes endshake under lateral shock. Its Glucydur balance is free-sprung, with Microstella nuts setting the rate without an index. KIF Elastor shock protection distinguishes it from the Paraflex-equipped Cal. 3132. At 5.85mm it is 0.15mm thinner than Cal. 3135 because it omits the date mechanism. The main plate is the dedicated part 3130-100, although some smaller components retain 3135 part numbers.
 
The 14060M initially used Cal. 3130 without COSC certification and carried a two-line dial. Certification arrived in late 2007, adding the two-line "Superlative Chronometer Officially Certified" inscription. The movement itself did not change.
 
The main wear point is the oscillating-weight axle, Rolex part 568, shared with Cal. 3135, 3155, 3175, and 3185. It runs in a plain sleeve bearing rather than a ball bearing. Once lubricant migrates, axle wear can produce rotor play and fine reddish dust. Replacing and riveting the axle is a routine service repair.
 
Cal. 3131, announced in 2007, adapts the 3130 for magnetic resistance with a blue Parachrom hairspring, a paramagnetic nickel-phosphorus escapement, and a two-part soft-iron shield around the movement. It powered the Milgauss 116400 and 116400GV, then the Air-King 116900.


<span id="cal-3186"></span>
<span id="cal-3132"></span>
=== Cal. 3186 ===
=== Cal. 3132 ===
[[File:Cal 3186 movement.webp|thumb|right|220px|Cal. 3186, engraved "3186"]]
[[File:Cal 3132 movement.webp|thumb|right|220px|Cal. 3132]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,601: Line 1,760:
|-
|-
| power reserve
| power reserve
| 50h
| 48h
|-
|-
| size
| size
| 28.5mm &times; 6.45mm
| 30.97mm (contested; 28.5mm also published)
|-
|-
| escapement
| escapement
Line 1,610: Line 1,769:
|-
|-
| balance
| balance
| Monometallic, free-sprung
| Monometallic Glucydur, free-sprung
|-
|-
| regulator
| regulator
Line 1,616: Line 1,775:
|-
|-
| shock
| shock
| Shock-absorber, pre-Paraflex
| Paraflex
|}
|}


2007–19, 31 jewels, 28,800 vph, 50 hours, hacking, quickset, chronometer — adds a Parachrom hairspring to the Cal. 3185 base, carrying late 16710 production into the ceramic-bezel GMT line, the 116710LN, 116710BLNR, and 116719BLRO.
Cal. 3132 powered the Explorer 214270 from 2010 to about 2020. It is a Cal. 3130 with a Parachrom hairspring and Paraflex shock protection, retaining 31 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, and chronometer certification.


Antiquorum's cataloguing is the fullest description of the movement in the public record: Cal. 3186, rhodium-plated, oeil de perdrix and fausses côtes decoration, 31 jewels, straight-line lever escapement, monometallic balance adjusted to temperatures and five positions, shock-absorber, self-compensating free-sprung Breguet balance spring, Microstella regulating screws, hack mechanism, from sale 214 in Geneva on 10 May 2009, lot 38. Bonhams describes the same caliber in a second 116718 with its own house wording — 31-jewel Cal. 3186, straight line lever escapement, monometallic balance, adjusted to heat, cold, isochronism and 5 positions, shock protection, self compensating balance spring — and the two agree on every mechanical point. One phrase in the Antiquorum text is boilerplate rather than observation: the balance spring is called blued steel, and on a 3186 it is Parachrom, a niobium-zirconium alloy whose colour comes from an oxide layer rather than from tempering. That spring is the caliber's reason for existing.
The base architecture remains a straight-line lever escapement with a free-sprung Glucydur balance under a full bridge, Microstella regulation, and no index. Paraflex replaced the 3130's KIF Elastor settings; Rolex claimed up to 50 per cent greater shock resistance. The blue Parachrom hairspring replaced Nivarox with a paramagnetic niobium-zirconium alloy whose colour comes from a patented oxide treatment.


Underneath the GMT work the movement is Cal. 3135 architecture, and Rolex states it outright: the factory parts sheet for the 3185 heads its specification block with Ø28.50mm, Ht 6.45mm, Train 28.800, 31 jewels and the line "Base Calibre 3135." The 3186 keeps that layout. That inheritance runs to the automatic work as well, including the oscillating-weight axle, Rolex part 568, shared with the 3130, 3135, 3155 and 3175 — the plain-bearing rotor post that wears once its oil has migrated and gets replaced and riveted at service.
Cal. 3132 brought Parachrom and Paraflex to the time-only professional line. Parachrom had appeared in Cal. 4130 in 2000, but the Submariner did not receive both features until Cal. 3230 in 2020.


Rolex introduced the 3186 as a running change rather than an announcement, which is why its start date is unsettled. The 2007 date reflects the steel transition collectors actually track, when late Z- and M-serial 16710s began leaving Geneva with the new caliber; the lowest documented 16710 example is a Z 5786xx, but the changeover was not sequential and Z-serials well above that number have turned up with 3185s inside. The gold references ran ahead of the steel. The Antiquorum lot above is a 116718 on a D-series case sold in August 2006 and catalogued as a 3186, which puts the movement in series production at least a year before the transition most owners date it to.
Both dial generations of the 214270 use Cal. 3132. The 2016 revision lengthened the hands and added luminous filling to the 3, 6, and 9 numerals, without changing the movement. Cal. 3132 also retains the 3130's plain-bearing oscillating-weight axle, which wears after its lubricant migrates.


The break from the 3185 is not only the hairspring, and it is narrower than the usual telling. Both calibers index the local-hour hand with a jumping-hour click: Rolex's parts sheet for the 3185 lists the click at 5242 and its spring at 5243, next to a friction spring for the additional hour wheel at 5226. What the 3186 does is rework that arrangement onto its own part series and pull the drive-train wheels closer together, taking the slack out of the independently-set hand. That produces the field diagnostic the market runs on. Jump the hour hand on a 3185 and the 24-hour hand twitches visibly as the play takes up; on a 3186 it stays put. No caseback needs to come off.
Rolex redefined Superlative Chronometer in 2015, changing the guaranteed rate from COSC's &minus;4/+6 seconds per day on the uncased movement to &minus;2/+2 on the cased watch after additional in-house testing. The movement did not change, so early and late 214270 examples carry different rate guarantees.


The click spring is also the caliber's known failure. When it goes, the hour hand stops indexing in clean one-hour steps and glides freely instead, which makes local-time setting useless and in the worst cases leaves the hand loose on its wheel. Rolex's own parts numbering records the response: the jumping-hour click begins as part 657, is superseded by 657-1, and then by 657-2, the later springs stronger and slightly larger than the first. Owners on RolexForums have documented the failure across the 16710, 16570, 116710, 116713, 116718 and 116719 and on into the Cal. 3187 that followed, with service centres replacing the spring at no charge on some watches long out of warranty and charging for it inside a full service on others. It is a spring rather than a catastrophe — nothing else is damaged when it breaks — but on a caliber produced in these numbers it is the first thing worth checking on an unserviced 3186 GMT.
<span id="cal-3135"></span>
 
=== Cal. 3135 ===
<span id="cal-3187"></span>
[[File:Cal 3135 movement.webp|thumb|right|220px|Cal. 3135, official Rolex photo, engraved "3135," 31 jewels]]
=== Cal. 3187 ===
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,647: Line 1,805:
|-
|-
| power reserve
| power reserve
| 48–50h (sources disagree)
| 48h
|-
|-
| size
| size
| 30.97mm (contested; 28.5mm also published)
| 28.5mm
|-
|-
| escapement
| escapement
Line 1,656: Line 1,814:
|-
|-
| balance
| balance
| Monometallic, free-sprung
| Free-sprung Glucydur, four Microstella nuts
|-
|-
| regulator
| regulator
| Microstella screws, no index
| Free-sprung, no index
|-
|-
| shock
| shock
| Paraflex
| KIF (never Paraflex)
|}
|}


An enlarged Cal. 3186, widened to push the date window outward for the 42mm Explorer II case — the same engineering trick Rolex used two years earlier on Cal. 3136 for the Datejust II. It powers the Explorer II 216570 exclusively, the first movement developed specifically for the Explorer line, running 2011 to 2021 before the 226570 and Cal. 3285 replaced it. Parachrom hairspring and Breguet overcoil carry over from the 3185/3186 GMT lineage, paired with an independently-adjustable 24-hour GMT hand and a Superlative Chronometer &minus;2/+2 rating. Paraflex does not carry over: the 3185 ran KIF Elastor settings and the 3187 is the first movement in this GMT family fitted with Rolex's own shock system.
Cal. 3135 ran from 1988 to 2021 with 31 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, quickset, and chronometer certification. It powered the 16610, 16613, and 16618 through the 116610 generation. The Submariner changed to Cal. 3235 with the 126610 on 1 September 2020, but the Oyster Perpetual Date 34 references 115200 and 115234 kept Cal. 3135 in production into 2021. Later end dates conflate it with Cal. 3131. The movement has rhodium plating, bevelled and polished screws, and a two-piece axle-style bidirectional rotor.
 
The conventional Swiss lever escapement is paired with a free-sprung Glucydur balance. With no index or curb pins, four Microstella nuts on the inside of the rim set the rate by changing the wheel's inertia. Older 1530-family balances place their adjustment screws on the outside. Cal. 3135 uses a Breguet overcoil and laser-welds the hairspring to its stud, replacing the glued joint used by Cal. 3035.


Auction descriptions of the 3187 are thin next to the 3186's. Sotheby's catalogues it as cal. 3187 automatic, 31 jewels and stops, so the mechanical detail comes from the relationship rather than from lot text. The 3187 is a 3186 on a larger baseplate with the surrounding parts reworked, which carries the straight-line lever escapement, the free-sprung monometallic balance under a full bridge, and the Microstella screws that set rate by inertia rather than by an index. Nothing in the regulating organ was redesigned; the movement grew to reach the date window at a wider radius, and everything that governs its rate came across unchanged.
The main architectural change from Cal. 3035 is the balance bridge. Part 3135-120 is secured at both ends and carries height-adjusting nuts, keeping the pivots aligned under load and allowing endshake adjustment without shims. It also prevents the hairspring from fouling a cantilevered balance cock, a known Cal. 3035 problem. Cal. 3135 increased the jewel count from 27 to 31 and uses a larger balance wheel.


Reference and caliber share a lifespan exactly. Rolex launched both at Basel in March 2011 for the Explorer II's fortieth anniversary, pulling the orange 24-hour hand back from the 1655 after two generations of red and white, and stretching the case to 42mm — which is what forced the movement to grow in the first place. The 216570 ran a full decade to 2021, and no other reference ever received the 3187, which leaves it among the very few modern Rolex calibers with a single home.
Cal. 3135 used KIF shock protection throughout its run and never received Paraflex. Rolex assigned new caliber numbers to Paraflex versions: 3130 became 3132, 3155 became 3156, and 3186 became 3187. The larger Paraflex date movement for the Datejust II was Cal. 3136. A 16610 or 116610 described as having Paraflex is misidentified.


Two documented military commissions sit on top of the ordinary run. Sotheby's sold a white-dial 216570, movement number 9C'034'251, from a 2012 series issued to members of the British Special Air Service, its case band engraved "Who Dares Wins" and its caseback carrying the winged-dagger badge above the original owner's initials and personal number, as lot 11 of Fine Watches Including Masterworks of Time. Bonhams sold a second commission, a 216570 numbered 40/48 from a limited series made for the UK Attack Helicopter Force, circa 2015. Both are unit-commissioned rather than ministry-issued, which puts them in a different class from a 5513 MilSub, and both are the only regiment-marked Explorer IIs in the auction record. Both run the 3187.
Parachrom arrived during the Cal. 3135 run, but the transition date is unsettled. The niobium-zirconium alloy receives a uniform anodised oxide layer about 50 nanometres thick, which gives the hairspring its blue colour and stabilizes its restoring torque. Published dates for its adoption in Cal. 3135 range from about 2005 to 2009, with transitional examples reported on both sides. The ceramic-bezel 116610 uses it consistently from 2010. The spring's colour provides only a rough dating marker.


The 3187 inherited the 3186's weak point along with its architecture. The jumping-hour click spring that lets the local-hour hand index in whole-hour steps fails the same way on early examples, the hand gliding instead of clicking, and owners have reported it on the 216570 as readily as on the ceramic GMTs. Rolex revised the part twice; a serviced example carries the later, stronger spring.
Two wear points sit in the automatic works. The anodised purple-red reversing wheels, part 3135-540, are visible through the rotor cutout and identify the movement without disassembly. Failure produces free rotor spin without winding or gritty manual winding. Epilame belongs across the reverser assembly, while oil is confined to the arbor and bearing points; oil on the teeth or clicks can jam the mechanism. The oscillating-weight axle, part 3135-568, runs in a plain jewelled sleeve. Wear causes a rattle, rotor contact with the caseback, and red dust in the movement. Rolex supplied mainsprings in standard part 3135-311 and weaker 3135-311-1 versions, a relevant distinction when assessing a rebuilt movement.


The &minus;2/+2 figure needs a date attached to it. Rolex redefined Superlative Chronometer in 2015, taking the guaranteed rate from COSC's &minus;4/+6 seconds a day on the bare movement to &minus;2/+2 on the cased watch, tested again in Rolex's own laboratories and sold under a green seal with a five-year international guarantee. The 216570 ran on both sides of that change. A 2012 example left Geneva under the older promise and a 2018 example under the newer one, with no mechanical difference between the two beyond regulation, so the tighter number belongs to the second half of the reference's life rather than to the caliber as such.
A freshly serviced Cal. 3135 should show about 270 to 310 degrees of amplitude when fully wound. More than 335 degrees can indicate that the mainspring bridle is slipping too late because it lacks braking grease; Rolex sets a minimum of 200 degrees after 24 hours in the worst position. Earlier movements carried COSC's &minus;4/+6 seconds-per-day standard. From 2015, Rolex applied its &minus;2/+2 Superlative Chronometer test to the complete watch without changing the caliber. Derivatives include Cal. 3155, 3175, 3185, 3186, 3187, and the no-date 3130, 3131, and 3132.


<span id="sport-modern"></span>
<span id="milgauss-family"></span>
== Modern sport calibers (1988–2020) ==
== Milgauss ==


The modern time-only line settles on the 31xx family, opening with Cal. 3000 as the first 28,800 vph no-date movement of the era and running through Cal. 3130 and 3132 in direct succession. Cal. 3135, the date-equipped counterpart introduced the same year as Cal. 3000, becomes the single dominant modern Rolex workhorse across three decades of Submariner Date production.
Rolex introduced the documented Milgauss calibers about fifty years apart. Rolex adapted its contemporary sport movements for the Milgauss: Cal. 1580 derives from the 1530 platform, and Cal. 3131 from Cal. 3130.


<span id="cal-3000"></span>
<span id="cal-1580"></span>
=== Cal. 3000 ===
=== Cal. 1580 ===
[[File:Cal 3000 movement.webp|thumb|right|220px|Cal. 3000]]
[[File:Cal 1580 movement.webp|thumb|right|220px|Cal. 1580, marked "26 Jewels, Adjusted Six 6 Positions" — EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,693: Line 1,853:
|-
|-
| jewels
| jewels
| 27
| 26
|-
|-
| frequency
| frequency
| 28,800 vph (4 Hz)
| 19,800 vph (2.8 Hz)
|-
|-
| power reserve
| power reserve
| 42h
| 48h
|-
|-
| size
| size
| 28.5mm × 5.8mm
| 28.5mm &times; 5.75mm
|-
|-
| balance
| escapement
| Adjustable-mass, flat hairspring
| Straight-line lever
|-
| balance
| Free-sprung monometallic, Microstella screws
|-
| regulator
| None &mdash; free-sprung
|-
| shock
| Shock absorber
|}
|}


1989–99, 27 jewels, 28,800 vph, 42 hours (some owners report 45–60 hours in practice), 28.5 × 5.8mm — the first 28,800 vph time-only movement of the modern era, based on Cal. 3035 and powering the 14000 Air-King, 14010, 14060 Submariner, and 14270 Explorer. Deliberately simplified against the outgoing 1570 generation: a flat hairspring with no Breguet overcoil, and an adjustable-mass balance with no separate regulator arm at all. The automatic-winding module runs oversized components, including PTFE-coated red-alloy click wheels, and watchmakers commonly single out the winding module as the best-finished part of an otherwise deliberately economical movement.
Cal. 1580 is associated exclusively with the [[Reference:1019|Milgauss 1019]] during its 1960&ndash;1988 run, subject to the early-production dating conflict below. It shares the 1530-derived platform with Cal. 1570 and 1575, and gained hacking around 1972. A soft-iron inner shield around the movement provides the magnetic protection, making the 1019 thicker than contemporary Submariner and GMT-Master cases using the same movement family. Parts interchange broadly across the 1520/1525/1530/1535/1555/1556/1560/1565/1570/1575/1580 group.
 
Cal. 1580 has 26 jewels, a straight-line lever escapement, a monometallic balance adjusted to temperature and five positions, shock protection, and a Breguet hairspring. Antiquorum describes the hairspring as free-sprung white metal with Microstella regulation. That matches Cal. 1560 and 1570 on the same platform, although no second auction house specifies the regulation system.
 
The case provides the magnetic shielding. A gilt-metal anti-magnetic cap and the surrounding inner case absorb the field. Cal. 1580 uses the standard 1530-family balance and hairspring inside the shielded case. Rolex added hacking in 1972 with the corresponding sport-caliber revision.
 
The factory caliber table introduces Cal. 1580 in 1963, three years after the 1019's generally accepted launch around 1960. It lists the earlier anti-magnetic Cal. 1065M, 1066M, and 1080 from 1955, and a Milgauss 6541 is documented with Cal. 1080. Published evidence does not settle whether the earliest 1019s used Cal. 1580 or one of these 1030-family movements.


<span id="cal-3035"></span>
<span id="cal-3131"></span>
=== Cal. 3035 ===
=== Cal. 3131 ===
[[File:Cal 3035 movement.webp|thumb|right|220px|Cal. 3035, engraved "3035," EmmyWatch]]
[[File:Cal 3131 movement.webp|thumb|right|220px|Cal. 3131 from a Milgauss 116400GV, auto bridge and gold reversing wheels]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,721: Line 1,896:
|-
|-
| jewels
| jewels
| 27
| 31
|-
|-
| frequency
| frequency
Line 1,728: Line 1,903:
| power reserve
| power reserve
| 48h
| 48h
|-
| size
| 28.5mm
|-
| escapement
| Nickel-phosphorus escape wheel & pallet fork
|-
|-
| balance
| balance
| Free-sprung, four Microstella screws
| Free-sprung monometallic, Microstella
|-
|-
| shock
| shock
| KIF Elastor
| KIF
|}
|}


1977–88, 27 jewels, 28,800 vph, 48 hours, hacking, quickset, chronometer — the first quickset Submariner caliber, in the 16800, 168000, 16808, and 16803. Free-sprung balance, four Microstella regulating screws, Breguet overcoil in Nivarox alloy, KIF Elastor shock protection, held on a cantilever balance cock rather than the full bridge Cal. 3135 introduces later — the hairspring is glued to the balance-cock stud here, where the 3135 switches to a laser-welded attachment. Quickset works by giving the crown an intermediate position that connects directly to the date wheel, bypassing the hour wheel entirely — on a non-quickset movement the only way to advance the date is to run the hands forward through midnight, sometimes dozens of times to skip a long month. The date wheel gear path runs differently through the movement than on a non-quickset caliber, which is why the feature can't be retrofitted after the fact.
Cal. 3131 is a no-date Cal. 3130 derivative announced at Baselworld 2007 for the [[Reference:116400|Milgauss 116400]] and 116400GV "Glace Verte." From 2016 it also powered the Air-King 40 reference 116900. Magnetic protection has three parts. A two-piece ferromagnetic shield encloses the movement, with one half secured on the dial side and the other beneath the outer caseback; the inner back carries a capital "B" and arrow, the symbol for magnetic flux density. The movement also uses a paramagnetic blue Parachrom hairspring and an amorphous nickel-phosphorus escape wheel and pallet fork.
 
Cal. 3131 remained COSC-certified throughout its run, with KIF shock protection and a conventional Swiss lever escapement. It never received Chronergy or Paraflex. Rolex applied the tighter &minus;2/+2 seconds-per-day Superlative Chronometer standard from 2015, so later 116900 and 116400GV examples carry the revised rating without a corresponding movement change. The Air-King remained in production to 2022 and the Milgauss to 2023.


<span id="cal-3135"></span>
<span id="daytona-manual"></span>
=== Cal. 3135 ===
== Daytona chronograph (manual-wind) ==
[[File:Cal 3135 movement.webp|thumb|right|220px|Cal. 3135, official Rolex photo, engraved "3135," 31 jewels]]
 
The manual-wind Daytona used Valjoux 72 architecture from 1963 through 1988. Across five caliber numbers, Rolex progressively refinished and re-rated the Valjoux 72 ébauche.
 
Valjoux joined the Ebauches SA group in 1944 and was later folded into ETA, though the Valjoux name remained in use through the end of Cal. 72 production in 1974. At least 62,000 Valjoux 72/23 movements are recorded in Rolex cases across more than 40 references, about 7 per cent of total output. Heuer, Universal Genève and Longines also used the base. Rolex examples differ in their finishing and adjustment.
 
<span id="cal-72"></span>
=== Cal. 72 ===
[[File:Cal 72 movement.webp|thumb|right|220px|Valjoux 72 ébauche, caliber "72" stamped at 6 o'clock beside the Valjoux logo, plate marked "Seventeen 17 Jewels Unadjusted," stock index regulator with F/A–S/R scale — the untouched configuration Rolex fitted as Cal. 72. This example's chronograph bridge is signed Heuer-Leonidas SA]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,746: Line 1,936:
|-
|-
| type
| type
| Automatic
| Manual
|-
|-
| jewels
| jewels
| 31
| 17
|-
|-
| frequency
| frequency
| 28,800 vph (4 Hz)
| 18,000 vph (2.5 Hz)
|-
|-
| power reserve
| power reserve
| 48h
| 48h
|-
| size
| 28.5mm
|-
|-
| escapement
| escapement
| Swiss lever
| Swiss lever
|-
| balance
| Free-sprung Glucydur, four Microstella nuts
|-
| regulator
| Free-sprung, no index
|-
|-
| shock
| shock
| KIF (never Paraflex)
| Incabloc
|}
|}


1988–2020, 31 jewels, 28,800 vph, 48 hours, hacking, quickset, chronometer — Rolex's thirty-year workhorse, running the 16610, 16613, and 16618 through to the 116610 generation and leaving the Submariner only when the 126610 arrived with Cal. 3235 in 2020. Rhodium-plated finish, beveled and polished chamfered screws, and a two-piece axle-style bidirectional rotor.
Used in the pre-Daytona ref. 6234 from about 1955 to 1961, Cal. 72 remained close to the Valjoux ébauche. Rolex retained its index regulator, flat hairspring and Incabloc protection. Auction records document the bare Cal. 72 designation on examples from 1957 and around 1960; published production dates for the 6234 end in either 1960 or about 1961.


The escapement is a conventional Swiss lever; the interest sits in the oscillator above it. The balance is Glucydur, the beryllium-bronze alloy Rolex had been using since the 1950s, and it runs free-sprung, with no index and no curb pins, so rate is set by turning four Microstella nuts and changing the wheel's inertia instead of the working length of the spring. Those nuts sit on the inside of the balance rim, a 3135-generation trait: the older 1530-family balances carry their equivalent adjustable screws on the outside, where a clockwise turn draws the screw inward and speeds the watch up. The hairspring terminates in a Breguet overcoil, and where Cal. 3035 glued its hairspring to the balance stud, the 3135 laser-welds it.
<span id="cal-72a"></span>
 
=== Cal. 72A ===
The architectural change from the 3035 is the balance bridge. The 3035 carried a cantilevered balance cock anchored at one end by a single screw; the 3135 replaced it with a bridge (part 3135-120) screwed down at both ends and carrying height-regulating nuts, which holds the pivots in alignment under load and makes endshake adjustable without shimming. Watchmakers who have had both apart describe the 3035's signature failures as broken automatic-weight axles and axle jewels plus a hairspring that fouls on the balance cock, the second of which the bridge answers directly. The 3135 also went from 27 jewels to 31 and took a larger balance wheel.
{| class="wikitable" style="width:280px; font-size:90%;"
 
Shock protection is the detail most often reported wrongly. For its entire run the base 3135 used KIF, the hinged spring-mounted setting Rolex bought from Kif Parechoc for decades. Paraflex, Rolex's own shock absorber, filed from a March 2005 priority by Mitchell Colle and Roman Voirol and published as EP1705537 and US7234859, never went into it. Rolex handled the upgrade by renumbering instead: the base date caliber stayed 3135 with KIF, while the Paraflex version became Cal. 3136, the physically larger movement built for the Datejust II in 2009. The same pattern runs across the family, 3130 to 3132, 3155 to 3156, 3186 to 3187, so a Paraflex caliber always carries its own number. Listings that credit a 16610 or a 116610 with Paraflex are describing a movement Rolex did not build.
 
The hairspring is the running change that lets a collector date a movement without opening the case, though not as precisely as usually claimed. Parachrom is a niobium-zirconium alloy with traces of titanium, vanadium and tantalum, patented by Rolex from a March 1999 priority filing by Jacques Baur and Patrick Sol. Nb-Zr grows an uneven oxide film in air, which shifts the spring's restoring torque and with it the rate; the fix was to force a uniform anodised layer of roughly 50 nanometres, and that is what turns the spring blue. The colour is a by-product of that treatment: vary the anodising voltage and the colour varies with it, and early prototypes came out greenish. When it reached the 3135 is unsettled. Parachrom appeared first in the Daytona's Cal. 4130 around 2000 and the blue anodised version followed mid-decade; for the 3135 itself Grail Watch Reference dates the change to 2009, other accounts put it nearer 2005, and watchmakers report transitional late 14060M and 114060M examples either side of the line. The ceramic-bezel 116610 of 2010 carries it consistently. Any single year is a rough marker, not a hard cut.
 
Two wear points define the caliber's service life, and both sit in the automatic works. The reversing wheels (Rolex part 3135-540, "reversing wheel, mounted") are anodised purple-red and visible straight through the rotor cutout, an easy no-disassembly identification marker; Rolex dates that red finish to 1957 and describes it as a surface treatment applied to aluminium for hardness. They are also the most commonly reported fault on the caliber, presenting as a rotor that spins freely without winding the mainspring, or as gritty manual winding. The correct treatment is epilame across the whole reverser assembly with oil confined to the arbor and bearing points, never the teeth or the clicks, since oil migrating between the teeth and the red disc eventually jams the mechanism. The second is the oscillating-weight axle (part 3135-568), which runs against a plain jewelled sleeve rather than a ball bearing and is the signature failure of a long-unserviced example: an audible rattle, the rotor striking the case back, and red wear-dust carried through the movement. Andrew Babanin's 2005 teardown and Ashton Tracy's 2018 write-up in the ''Horological Journal'' reach the same conclusion thirteen years apart. Rolex stocked the mainspring in two factory strengths, 3135-311 and the weaker 3135-311-1, which is worth knowing on a movement someone else has rebuilt.
 
For a health check, a freshly serviced 3135 should show roughly 270 to 310 degrees of amplitude fully wound; much above 335 suggests the mainspring is slipping its bridle too late for want of braking grease, and Rolex's own timing procedure sets the floor at 200 degrees after 24 hours in the worst position. On certification, every 3135 went to COSC as a bare movement against the -4/+6 seconds-per-day standard. In 2015 Rolex redefined its own Superlative Chronometer marking to -2/+2 seconds per day measured on the finished, cased watch and applied it across the catalogue, so the last five years of 3135 production were held to the tighter in-house figure with the movement itself unchanged. The dial text is the tell, not the caliber. Derivatives run to the 3155 (day-date), 3175, 3185 and 3186 (GMT-Master II, the 3186 gaining an independently adjustable local-hour hand), 3187 (Explorer II 216570, adding Paraflex), and the date-less 3130, 3131 and 3132.
 
<span id="milgauss-family"></span>
== Milgauss ==
 
Milgauss is Rolex's anti-magnetic line, and its two documented calibers sit half a century apart on two different base architectures — one built on the 1530-derived sport platform, the other on the modern date-less 3130 — evidence the anti-magnetic engineering gets bolted onto whatever mainstream movement is current rather than kept as its own standalone design lineage.
 
<span id="cal-1580"></span>
=== Cal. 1580 ===
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
! value
! value
|-
|-
| type
| type
| Automatic
| Manual
|-
|-
| jewels
| jewels
| 26
| 17
|-
|-
| frequency
| frequency
| 19,800 vph (2.8 Hz)
| 18,000 vph (2.5 Hz)
|-
|-
| power reserve
| power reserve
| 48h
| 48h
|-
| size
| 28.5mm &times; 5.75mm
|-
|-
| escapement
| escapement
| Straight-line lever
| Swiss lever
|-
| balance
| Free-sprung monometallic, Microstella screws
|-
| regulator
| None &mdash; free-sprung
|-
|-
| shock
| shock
| Shock absorber
| Incabloc
|}
|}


Powers the [[Reference:1019|Milgauss 1019]] exclusively across its entire 1960&ndash;1988 run, one of the longest single-caliber, single-reference pairings in Rolex's catalogue. It shares the 1530-derived platform with Cal. 1570 and 1575, with hacking added mid-production around 1972. The anti-magnetic engineering lives in the case rather than the movement: a soft-iron inner shield forms a Faraday cage around the caliber, which is why the 1019's case runs thicker than its Submariner and GMT-Master contemporaries built on the same movement family. Parts interchange broadly across the whole 1520/1525/1530/1535/1555/1556/1560/1565/1570/1575/1580 group.
Cal. 72A appears in late ref. 6234s from the late 1950s to about 1961. It retains the index regulator and flat hairspring that Cal. 72B would replace, making it a Rolex-finished but otherwise conventional Valjoux 72 execution. The meaning of the ROW stamp remains uncertain: Sotheby's associates it with US importation, while Grail Watch Reference reads it as Rolex Werke. Neither interpretation is supported by a known Rolex document.


Antiquorum's fullest description, from a New York sale in May 2004, reads: rhodium-plated, 26 jewels, straight line lever escapement, monometallic balance adjusted to 5 positions and temperature, shock-absorber, self-compensating Breguet balance-spring, Microstella regulating screws. A second Antiquorum lot from October 2005 sharpens the balance spring to "free-sprung white metal Breguet." Phillips corroborates the escapement and balance independently, cataloguing a 1019 in Hong Kong in December 2015 as a nickel lever movement, 26 jewels, mono-metallic balance &mdash; and the 26-jewel count is unanimous across Christie's, Sotheby's, Phillips and Antiquorum lots spanning 2015 to 2021. The free-sprung Microstella regulation rests on Antiquorum's wording alone; it matches the balance package Cal. 1560 and 1570 carry on the same platform, but no second house spells it out, so it should be read as strongly indicated rather than independently confirmed.
<span id="cal-72b"></span>
 
=== Cal. 72B ===
The anti-magnetic construction deserves stating precisely, because the shielding is case furniture and none of it sits inside the caliber. Every major house describes a discrete component: Antiquorum's case line for the 2004 lot reads "three-body, polished and brushed, screwed-down case back and crown, gilt metal anti-magnetic protecting cap," and Christie's, Sotheby's and Phillips all name the same gilt-metal anti-magnetic cap in their own case descriptions. Cal. 1580 itself is a standard 1530-family movement with no special metallurgy in the balance or hairspring &mdash; the ferrous cap over the movement and the inner case around it absorb the field, and the caliber inside is protected rather than immune. That is also why the 1580 could stay on the ordinary sport-caliber upgrade path, picking up hacking in 1972 alongside its siblings.
[[File:Cal 72B movement.webp|thumb|right|220px|Rolex-signed Valjoux 72-family movement, seventeen jewels — caliber sub-variant not distinguishable from the engraving alone]]
 
One dating question stays open. The factory caliber table enters Cal. 1580 in 1963, marks it hack-after-1972, and gives its base as Cal. 1530 at 28.5 by 5.75mm and 19,800 vph &mdash; but the 1019 launched around 1960, three years earlier. The anti-magnetic calibers preceding it in that table are the 1030-family 1065M, 1066M and 1080, all entered in 1955 and all flagged anti-magnetic, and Bonhams catalogued a Milgauss 6541 on Cal. 1080 in London in December 2009 with a free-sprung Breguet balance spring of its own. Whether the earliest 1019s shipped on a 1580 or on one of those 1030-family movements is not settled by the sources here, and the claim of a single caliber across the full run should be read against that gap.
 
<span id="cal-3131"></span>
=== Cal. 3131 ===
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,841: Line 1,991:
|-
|-
| type
| type
| Automatic
| Manual
|-
|-
| jewels
| jewels
| 31
| 17
|-
|-
| frequency
| frequency
| 28,800 vph (4 Hz)
| 18,000 vph (2.5 Hz)
|-
|-
| power reserve
| power reserve
| 48h
| 48h
|-
| size
| 28.5mm
|-
|-
| escapement
| escapement
| Nickel-phosphorus escape wheel & pallet fork
| Swiss lever
|-
|-
| balance
| balance
| Paramagnetic blue Parachrom
| Microstella, adjustable inertia
|-
|-
| shock
| shock
| KIF
| KIF (often Flector)
|}
|}


A date-less Cal. 3130 derivative built for the [[Reference:116400|Milgauss 116400]] and 116400GV "Glace Verte" (2007–2023), and the Air-King 40 ref. 116900 (2016–2022). Anti-magnetism runs three layers deep rather than one: a two-part soft-iron shield around the movement — its interior engraved with a "B" and arrow, the symbol for magnetic flux density, visible only to Rolex-trained watchmakers — a paramagnetic blue Parachrom hairspring, and an escape wheel and pallet fork machined in amorphous nickel-phosphorus rather than steel, the detail most write-ups skip. COSC-certified for its entire run, the 3131 never received the Chronergy escapement or the tightened &minus;2/+2 Superlative rating that later reached the rest of the sport line — the Milgauss was discontinued before that upgrade cycle arrived.
Used in the ref. 6238 and the last 6234s, Cal. 72B marks Rolex's first substantial reworking of the Valjoux base. The index regulator gave way to a Microstella adjustable-inertia balance, the flat hairspring to a Breguet overcoil, and Incabloc protection to KIF, often in its clover-shaped Flector form. The caliber also has the earlier screwed setting lever, later replaced by a pusher type.


<span id="daytona-manual"></span>
The transition date is disputed. Dody Giussani's text for ''Ultimate Rolex Daytona'' dates the complete replacement of Cal. 72A to 1966, while auction records identify Cal. 72B in ref. 6234 examples from around 1961. Giussani finds no substantial mechanical difference between the 72B and 722 and notes that Rolex used both names in its technical documents. The regulating organ changed before Rolex consistently adopted the later caliber name.
== Daytona chronograph (manual-wind) ==


The manual-wind Daytona stays on Valjoux 72 architecture for its entire first chapter, 1963 through 1988, moving through five caliber numbers as Rolex progressively finished and then re-rated the same base ébauche. Valjoux was an independent Swiss ébauche manufacturer &mdash; it built the unfinished movement blank, not a complete Rolex-designed caliber &mdash; absorbed into the Ebauches SA holding group in 1944 and folded more fully into what became ETA in 1965, though movements kept the Valjoux name through the end of 72 production in 1974. Rolex was Valjoux's biggest single customer for this caliber: research into surviving case numbers puts at least 62,000 Valjoux 72/23 movements inside Rolex cases across more than 40 references, something like 7% of total Valjoux 72 output, Rolex's demand alone likely helped keep the column-wheel chronograph in production as long as it stayed viable. Heuer, Universal Genève, Longines and others built chronographs on the same base; what distinguished a Rolex example was the finishing and rate adjustment applied after the ébauche left Valjoux, not a different movement underneath.
<span id="cal-722"></span>
 
=== Cal. 722 ===
<span id="cal-72"></span>
[[File:Cal 722 movement.webp|thumb|right|220px|Rolex-signed Valjoux 72-family movement, seventeen jewels — caliber sub-variant not distinguishable from the engraving alone]]
=== Cal. 72 ===
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,892: Line 2,037:
| escapement
| escapement
| Swiss lever
| Swiss lever
|-
| balance
| Microstella, adjustable inertia
|-
|-
| shock
| shock
| Incabloc
| KIF (often Flector)
|}
|}


1960–65, 17 jewels, 18,000 vph, 48 hours — a bare Valjoux 72 with minimal Rolex finishing, in the 6234 and earliest 6238. Rolex left the stock Valjoux regulating organ untouched at this stage: index regulator, flat hairspring, factory Incabloc shock protection — the standard configuration off any Valjoux 72 ébauche, not yet a Rolex-specific balance package.
Cal. 722 powered the refs. 6239, 6240 and 6241, including examples with "Paul Newman" dials. Its column wheel controls a horizontal clutch through a coupling yoke. Engagement can make the chronograph hand jump slightly forward or back at the start, a trait later removed by the vertical clutch in Cal. 4130.


<span id="cal-72a"></span>
The position of the "Rolex Genève" inscription on the dial-side plate distinguishes Cal. 722 from the 722-1 that followed. The designations otherwise overlap: Christie's records Cal. 72B, 722 and 722-1 across ref. 6241 production. The engraving on the movement is more reliable than a date-based attribution.
=== Cal. 72A ===
 
<span id="cal-722-1"></span>
=== Cal. 722-1 ===
[[File:Cal 722-1 movement.webp|thumb|right|220px|Rolex-signed Valjoux 72-family movement, seventeen jewels — caliber sub-variant not distinguishable from the engraving alone]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,917: Line 2,068:
| 48h
| 48h
|-
|-
| escapement
| balance
| Swiss lever
| Microstella (inherited from 722)
|-
|-
| shock
| shock
| Incabloc
| KIF
|}
|}


Early-to-mid 1960s, 17 jewels, 18,000 vph, 48 hours — a Rolex-finished intermediate step between Cal. 72 and 72B; thinly documented in the collector record. It keeps the same stock regulating organ as Cal. 72: index regulator, flat hairspring, Incabloc shock — the finishing changed, the internals did not yet.
Introduced in 1967, Cal. 722-1 was the last 18,000 vph Daytona caliber before Cal. 727 raised the frequency. Rolex described it as a Valjoux 72A-based mechanism with the same dimensions as its predecessor; the changes were internal.
 
The hour-recorder conveyor gained an eccentric pivot and wing-shaped spring, allowing more precise engagement with the hour wheel. A guard spring above the balance was intended to keep the hairspring on its stud support under shock. Giussani records that the guard had already appeared inconsistently on Cal. 722 and caused problems of its own, so many surviving examples of both calibers lack it.


<span id="cal-72b"></span>
<span id="cal-727"></span>
=== Cal. 72B ===
=== Cal. 727 ===
[[File:Cal 72B movement.webp|thumb|right|220px|Rolex-signed Valjoux 72-family movement, seventeen jewels — caliber sub-variant not distinguishable from the engraving alone]]
[[File:Cal 727 movement.webp|thumb|right|220px|Cal. 727 (right, engraved 727, Daytona ref 6265), specialist comparison photo via Perezcope]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,940: Line 2,093:
|-
|-
| frequency
| frequency
| 18,000 vph (2.5 Hz)
| 21,600 vph (3 Hz)
|-
|-
| power reserve
| power reserve
Line 1,952: Line 2,105:
|-
|-
| shock
| shock
| KIF (often Flector)
| KIF
|}
|}


1962–65, 17 jewels, 18,000 vph, 48 hours: the final pre-722 Valjoux 72 execution, in the early 6238. This is where Rolex actually intervenes in the movement rather than just finishing it: the stock index regulator and flat hairspring are replaced with a Microstella adjustable-inertia balance and a Breguet overcoil, regulating by inertia rather than a curb-pin index, and the shock system switches to KIF, often the clover-shaped Flector variant. Watch historian Pucci Papaleo, who has serviced large numbers of these movements, states there is no substantial mechanical difference between the 72B and the 722 that follows it — the regulating-organ swap described here is what actually separates 72B from 72A, not the 72B-to-722 rename. The name change reflects Rolex re-branding the same finished movement for its own advertising and parts catalogues, not a new architecture.
Cal. 727 raised the Valjoux 72 frequency from 18,000 to 21,600 vph and powered the refs. 6262, 6263, 6264 and 6265 from 1970 until 1988. A genuine example has a Breguet overcoil and a bevelled inner edge on the KIF shock-spring retaining ring. These details, together with the engraved caliber number, help distinguish an original movement from a substituted or counterfeit one.
 
<span id="daytona-auto"></span>
== Daytona chronograph (automatic) ==


<span id="cal-722"></span>
<span id="cal-4030"></span>
=== Cal. 722 ===
=== Cal. 4030 ===
[[File:Cal 722 movement.webp|thumb|right|220px|Rolex-signed Valjoux 72-family movement, seventeen jewels — caliber sub-variant not distinguishable from the engraving alone]]
[[File:Cal 4030 movement.webp|thumb|right|220px|Cal. 4030, engraved 4030, thirty-one jewels]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,965: Line 2,121:
|-
|-
| type
| type
| Manual
| Automatic
|-
|-
| jewels
| jewels
| 17
| 31
|-
|-
| frequency
| frequency
| 18,000 vph (2.5 Hz)
| 28,800 vph (4 Hz)
|-
|-
| power reserve
| power reserve
| 48h
| 52–54h (sources disagree)
|-
| balance
| Free-sprung Breguet
|-
|-
| escapement
| escapement
| Swiss lever
| Swiss lever
|-
| balance
| Microstella, adjustable inertia
|-
| shock
| KIF (often Flector)
|}
|}


1963–69, 17 jewels, 18,000 vph, 48 hours — the first Rolex-stamped Valjoux 72, powering the original 6239 alongside the 6240 and 6241 generation, the run that includes the "Paul Newman" dial variants. Rolex used "72B" and "722" interchangeably on its own technical documentation for the same regulating package — Microstella balance, Breguet overcoil, KIF shock, column-wheel chronograph with yoke coupling.
Launched with the ref. 16520 in 1988, Cal. 4030 was a heavily reworked Zenith El Primero 400 and the last externally designed movement used by Rolex. Rolex removed the date, reduced the frequency from 36,000 to 28,800 vph and changed more than half of the components. A Breguet overcoil replaced the flat hairspring, while a free-sprung Glucydur balance with Microstella regulation and KIF protection replaced the Zenith oscillator. The chronograph retained a column wheel and horizontal clutch.
 
Published power-reserve figures split between 52 and 54 hours, with no known Rolex document settling the difference. The photographed movement is signed "MONTRES ROLEX S.A. GENEVA SWISS, ADJ. 5 POSITIONS TEMPERATURE, THIRTY-ONE JEWELS" and stamped "4030."


<span id="cal-722-1"></span>
<span id="cal-4130"></span>
=== Cal. 722-1 ===
=== Cal. 4130 ===
[[File:Cal 722-1 movement.webp|thumb|right|220px|Rolex-signed Valjoux 72-family movement, seventeen jewels — caliber sub-variant not distinguishable from the engraving alone]]
[[File:Cal 4130 movement.webp|thumb|right|220px|Cal. 4130 movement detail, bridge marked "4130"]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 1,996: Line 2,151:
|-
|-
| type
| type
| Manual
| Automatic
|-
|-
| jewels
| jewels
| 17
| 44
|-
|-
| frequency
| frequency
| 18,000 vph (2.5 Hz)
| 28,800 vph (4 Hz)
|-
|-
| power reserve
| power reserve
| 48h
| 72h
|-
| escapement
| Swiss lever, 52&deg; lift angle
|-
|-
| balance
| balance
| Microstella (inherited from 722)
| Free-sprung, four gold Microstella nuts
|-
|-
| shock
| shock
Line 2,014: Line 2,172:
|}
|}


1969–70, 17 jewels, 18,000 vph, 48 hours — a transitional revision of Cal. 722 bridging into the higher-beat Cal. 727 era. Unlike the largely cosmetic 72B-to-722 rename, this one is a genuine mechanical change: Rolex altered the shape of the hour-recorder conveyor in the chronograph coupling mechanism so it engaged more smoothly with its driving wheel, the fix that let the higher-beat 727 run reliably at 21,600 vph shortly after. It also adds a hairspring guard spring, a metal sheet stopping the hairspring sliding over its stud support under impact — introduced here but not consistently fitted, so many surviving movements lack it.
Cal. 4130 was Rolex's first chronograph movement of its own design, launched with the ref. 116520 in 2000. Its column wheel and vertical clutch provide clean chronograph engagement without the hand jump associated with Cal. 4030. The movement uses 201 components, about 20 per cent fewer than its predecessor, and twelve types of screw rather than more than forty.
 
The rotor runs on a ball bearing; the Cal. 3135 generation uses a jewelled sleeve. Claims that the bearing is ceramic lack support from Rolex or specialist documentation. The free-sprung balance sits under a transversal bridge and uses KIF protection. Chronergy, Paraflex, an optimised rotor bearing and Côtes de Genève arrived with Cal. 4131 in 2023. The display back also belongs to that successor and was limited to platinum; every Cal. 4130 Daytona has a solid caseback.
 
Parachrom was fitted from launch, but the blue version is variously dated between about 2005 and 2007 without a supporting Rolex document. Later examples were rated to Rolex's −2/+2 seconds-per-day standard after its introduction in 2015. Cal. 4130 continued through the ref. 116500LN until Cal. 4131 replaced it in March 2023.
 
<span id="day-date-family"></span>
== Day-Date ==
 
Day-Date calibers form their own family. Four-digit references set both calendar displays through the hands; five-digit references introduced quickset.


<span id="cal-727"></span>
<span id="cal-1055"></span>
=== Cal. 727 ===
=== Cal. 1055 ===
[[File:Cal 727 movement.webp|thumb|right|220px|Cal. 727 (right, engraved 727, Daytona ref 6265), specialist comparison photo via Perezcope]]
[[File:Cal 1055 movement.webp|thumb|right|220px|Cal. 1055, period parts-catalogue illustration, front and back]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 2,024: Line 2,191:
|-
|-
| type
| type
| Manual
| Automatic
|-
|-
| jewels
| jewels
| 17
| 25
|-
|-
| frequency
| frequency
| 21,600 vph (3 Hz)
| 18,000 vph (2.5 Hz)
|-
|-
| power reserve
| power reserve
| 48h
| 42h
|-
|-
| escapement
| escapement
| Swiss lever
| Straight-line lever
|-
|-
| balance
| balance
| Microstella, adjustable inertia
| Monometallic
|-
|-
| shock
| shock
Line 2,045: Line 2,212:
|}
|}


1970–88, 17 jewels, 21,600 vph, 48 hours: the higher-beat Valjoux 72 that lifts the rate from 18,000 to 21,600 vph and runs through the 6262, 6263, 6264, and 6265 until the manual-wind Daytona era closes in 1988. The photographed comparison is a specialist side-by-side of two period movements, one catalogued as a "Rolex Daytona Ref. 6263" in quotation marks, the other a confirmed genuine 6265 with "727" plainly engraved. Specialist forensic teardown work uses the Breguet overcoil and the bevelled inner edge of the KIF shock-spring retaining ring as authentication points on this caliber specifically, distinguishing genuine examples from fakes that get the case right but not the movement detail. It doubles as a useful authentication reference generally: matching a movement's engraved caliber number against what a listing claims separates a documented example from a franken watch.
Cal. 1055 was Rolex's first day-and-date movement, used from 1956 to 1959 in the refs. 6510, 6511, 6611, 6612 and 6613. Its rhodium-plated bridges carry oeil-de-perdrix ("partridge-eye") circular graining rather than Côtes de Genève. Documented examples were adjusted to temperature and five positions.
 
The ref. 6611 replaced the 6511 in 1957 with an improved chronometer-certified version engraved 1055B on the bridge. Its dial reads "Superlative Chronometer Officially Certified" rather than the earlier "Officially Certified Chronometer."


<span id="daytona-auto"></span>
The arrival of the free-sprung Microstella balance is disputed. The usual account places it with the 66xx revision, but an auction description identifies a first-generation 6511 as free-sprung. Neither generation has quickset or hacking.
== Daytona chronograph (automatic) ==


<span id="cal-4030"></span>
<span id="cal-1555"></span>
=== Cal. 4030 ===
=== Cal. 1555 ===
[[File:Cal 4030 movement.webp|thumb|right|220px|Cal. 4030, engraved 4030, thirty-one jewels]]
[[File:Cal 1555 movement.webp|thumb|right|220px|Cal. 1555, rotor bridge detail]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 2,061: Line 2,229:
|-
|-
| jewels
| jewels
| 31
| 25
|-
|-
| frequency
| frequency
| 28,800 vph (4 Hz)
| 18,000 vph (2.5 Hz)
|-
|-
| power reserve
| power reserve
| 52–54h (sources disagree)
| 42h
|-
| size
| 7.03mm
|-
| escapement
| Swiss lever (Cal. 1530 train)
|-
|-
| balance
| balance
| Free-sprung Breguet
| Free-sprung beryllium-bronze, Microstella screws
|-
|-
| escapement
| shock
| Swiss lever
| KIF Flector
|}
|}


1988–2000, 31 jewels, 28,800 vph, 54 hours, chronometer — Rolex's most disputed movement specification, and the last foreign-sourced caliber in its modern line. The working outline is a heavily reworked Zenith El Primero base, launched with the 16520 for a twelve-year run; serious sources agree on the 28,800 vph rate, a free-sprung Breguet balance, and no date function, but diverge on the exact length of Rolex's modification list and quote the power reserve as either 52 or 54 hours depending on source. The photographed example, marked "MONTRES ROLEX S.A. GENEVA SWISS, ADJ. 5 POSITIONS TEMPERATURE, THIRTY-ONE JEWELS" with "4030" in a small stamped box, is a clean confirmation of the caliber regardless of which modification-list version a given source favors.
Cal. 1555 powered early four-digit Day-Dates, including the refs. 1803, 1804, 1806, 1807 and 1811, from 1959 to about 1967. It combines the day-and-date architecture of Cal. 1055 with the plate and most running components of Cal. 1530. Its distinct parts are concentrated in the motion and calendar work, some shared with the contemporary Datejust Cal. 1575.
 
The Swiss lever escapement comes from Cal. 1530 and uses KIF Flector protection. The free-sprung balance uses a Nivarox Breguet overcoil and screw-shaped Microstella adjusters. Rolex did not adopt the later nut-shaped Microstella components until 1983.
 
Cal. 1555 does not hack; unlike the 1972 revision of Cal. 1556, its parts list has no balance-stop spring. Wear in the mainspring-barrel bearing is a known fault. As the plate and bridge bores wear out of round, the barrel can tilt and reduce amplitude; Rolex supplied a replacement upper barrel bush for the repair.
 
Five stainless-steel Day-Dates are publicly known, none with a listed reference or case serial. Christie's records movement numbers 0004547, 0005073, DD411420, DD14749 and DD081221. Their casebacks are signed Rolex and stamped "Stainless Steel"; the known examples have French day discs, black hands and silvered dials, with provenance linked to former Rolex watchmakers. Christie's identifies them as workshop test pieces. Movement DD411420 is engraved 1555 but runs at the Cal. 1556 frequency of 19,800 vph, placing it between the two generations.
 
The prototype's jewel count is disputed. Antiquorum gives 25, matching the bridge signature, while Phillips gives 26, the figure for Cal. 1556. At 7.03mm, Cal. 1555 is the thickest member of the 1500 series. The stepped "pie-pan" dial remained in use until about 1970, outlasting the caliber.


<span id="cal-4130"></span>
<span id="cal-1556"></span>
=== Cal. 4130 ===
=== Cal. 1556 ===
[[File:Cal 4130 movement.webp|thumb|right|220px|Cal. 4130 movement detail, bridge marked "4130"]]
[[File:Cal 1556 movement.webp|thumb|right|220px|Cal. 1556]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
! value
! value
Line 2,089: Line 2,271:
|-
|-
| jewels
| jewels
| 44
| 26
|-
|-
| frequency
| frequency
| 28,800 vph (4 Hz)
| 19,800 vph (2.8 Hz)
|-
|-
| power reserve
| power reserve
| 72h
| 42h
|-
|-
| escapement
| escapement
| Swiss lever, 52&deg; lift angle
| Swiss lever, 52&deg; lift angle
|-
| balance
| Free-sprung, four gold Microstella nuts
|-
|-
| shock
| shock
| KIF
| KIF Flector, both balance pivots
|}
|}


2000–2023, 44 jewels, 28,800 vph, 72 hours, chronometer: Rolex's first fully in-house chronograph movement, launched with the 116520. Column-wheel construction with a vertical clutch, 201 components, and the first Rolex chronograph to run on a ceramic ball-bearing rotor (7 balls on 3 screws) rather than a sleeve bearing, cutting the part count below the Cal. 4030 it replaced despite the added complexity. A conventional Swiss lever escapement, not the Chronergy escapement that arrives only with the 4131 successor — the free-sprung balance is held by a transversal bridge screwed at both ends rather than a cock, the bridge's own rigidity doubling as a shock-resistance measure, backed by KIF shock protection rather than the later Paraflex system. Solid caseback only; the display back doesn't arrive until the 4131 successor in 2023 either. The vented rotor carries a proprietary Rolex striping pattern, a visual tell against generic aftermarket rotors sometimes swapped into grey-market builds. Parachrom hairspring from launch, though sources disagree on when the blue oxide-coated version specifically arrived — readings range from 2005 to "all Daytona movements since 2007," not fully reconciled. It powered the whole pre-ceramic in-house Daytona generation and carried forward into the 116500LN.
Cal. 1556 succeeded the 1555 around 1965 and powered the mid- and late four-digit Day-Date until 1977 or 1978. A revised gear train raised the frequency, while a jewel at the top of the centre wheel brought the count to 26. Its rhodium-plated movement has perlage finishing, a full balance bridge and a screwed balance with two gold, star-shaped Microstella regulating screws. Hacking was added during production in 1972 without a new caliber designation; earlier examples do not hack.


<span id="day-date-family"></span>
<span id="cal-1566"></span>
== Day-Date ==
=== Cal. 1566 ===
 
The Day-Date runs on its own caliber family, entirely separate from the sport and Oyster Perpetual movements documented above. Quickset arrives only with the 5-digit generation — every 4-digit Day-Date sets the day and date exclusively by running the hands through midnight.
 
<span id="cal-1055"></span>
=== Cal. 1055 ===
[[File:Cal 1055 movement.webp|thumb|right|220px|Cal. 1055, period parts-catalogue illustration, front and back]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 2,125: Line 2,298:
|-
|-
| jewels
| jewels
| 25
| 26
|-
| frequency
| 18,000 vph (2.5 Hz)
|-
| power reserve
| 42h
|-
|-
| escapement
| escapement
Line 2,137: Line 2,304:
|-
|-
| balance
| balance
| Monometallic
| Monometallic, free-sprung Breguet spring
|-
| shock
| KIF
|}
|}


1956–1959, 25 jewels, 18,000 vph, 42 hours — Rolex's first day-and-date caliber, carried by the originals-era 6510, 6511, 6611, 6612, and 6613. Straight-line Swiss lever escapement, KIF shock protection, monometallic balance adjusted to temperature and five positions, self-compensating Breguet balance spring. Rhodium-plated, with oeil-de-perdrix ("partridge-eye") circular graining on the finish rather than Côtes de Genève stripes. The generation-1 movement (6510/6511) pre-dates COSC certification; the generation-2, engraved "1055B" on the bridge rather than "1055," adds full COSC rating and carries "Superlative Chronometer Officially Certified" on the dial in place of the earlier "Officially Certified Chronometer" script. Sources disagree on whether the free-sprung Microstella balance is a 1055B-only upgrade or already present on the base 1055 — both readings appear in the record, unresolved. No quickset, no hacking, on either generation.
Cal. 1566 was built for one case, the platinum [[Reference:1831|Day-Date 1831]] commissioned for the Shah of Iran and delivered from 1977. At 290 grams, it is the heaviest production Rolex. The rhodium-plated movement has a free-sprung Breguet hairspring, Microstella regulation and hacking. Sources record either eight or nine examples. One concordance assigns the ref. 1831 to Cal. 1556, while auction houses that examined the watches identify Cal. 1566.


<span id="cal-1555"></span>
<span id="cal-3055"></span>
=== Cal. 1555 ===
=== Cal. 3055 ===
[[File:Cal 1555 movement.webp|thumb|right|220px|Cal. 1555, rotor bridge detail]]
[[File:Cal 3055 movement.webp|thumb|right|220px|Cal. 3055, period parts-catalogue illustration with day-disc]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 2,156: Line 2,320:
|-
|-
| jewels
| jewels
| 25
| 27
|-
|-
| frequency
| frequency
| 18,000 vph (2.5 Hz)
| 28,800 vph (4 Hz)
|-
|-
| power reserve
| power reserve
| 42h
| 48h
|-
| size
| 7.03mm
|-
|-
| escapement
| escapement
| Swiss lever (Cal. 1530 train)
| Swiss lever
|-
|-
| balance
| balance
| Free-sprung beryllium-bronze, Microstella screws
| Free-sprung Glucydur, Microstella
|-
|-
| shock
| shock
| KIF Flector
| KIF
|}
|}


1959–c.1967, 25 jewels, 18,000 vph, 42 hours, chronometer, still non-quickset and non-hacking — the movement carrying the early 4-digit Day-Date (1803, 1804, 1806, 1807, 1811). Its parentage gets stated two ways and both are defensible: it inherits the day-and-date architecture Cal. 1055 established in 1956, and it is built on the Cal. 1530 plate already running under the sport watches. Rolex's own part numbering settles which claim carries more weight. Almost everything in a 1555 outside the calendar work is a 1530 component — balance staff 7864, pallet staff 7847, escape-wheel jewels 7937, barrel drum and arbor 7826/7827, crown and ratchet wheels 7872/7876, sliding pinion 7871, and the whole automatic-winding group from 7906 through 7919. What actually carries a 1555 number is the motion and calendar work: centre wheel 8001, cannon pinions 8002 and 8004, cam-yoke jewel 8007, cam-yoke spring 8008, calendar-wheel stud 8011. Three of those five are shared outright with Cal. 1575, the Datejust movement of the same years, so the President and the Datejust were running common calendar hardware with a day disc laid over the top.
Cal. 3055 powered the refs. 18038, 18048, 18078 and early 18238 from 1977 to 1988. It introduced quickset for the date, while the day still advanced through the motion of the hands. The balance cock provides the clearest visual distinction from Cal. 3155, which uses a full transversal bridge. Common references give a height of 6.3mm, but Rolex's parts diagram specifies 7.11mm.


The escapement is the 1530's Swiss lever, unchanged, and the shock protection is KIF rather than Incabloc. Two independent lines of evidence agree: the trade parts catalogues list the upper shock spring for a 1555 under the 1530's number 7934 and label it old-type KIF, and Phillips prints "KIF flector shock absorbers" in its own cataloguing of the caliber. The balance is free-sprung with a Nivarox Breguet overcoil and Microstella regulation, no index pin bearing on the spring — the same package Cal. 1560 was carrying on the sport side from the same 1959 start. One detail here needs correcting. The Microstella components on a 1555 are screws, not the four gold nuts of the modern calibers: Rolex's own account of the system says it was screw-shaped when first developed in 1957, and Rolex's 1978 service documentation still describes screws on the successor 1556, with the changeover to nut-shaped Microstella coming only in 1983. Descriptions that put four Microstella nuts on this caliber are reading a modern balance backwards into a 1959 one.
<span id="cal-3155"></span>
 
=== Cal. 3155 ===
The absence of hacking shows up in the parts list rather than resting on assertion. When the 1556 gained hacking in 1972 it picked up a balance stop spring carried under Cal. 1570's number 8115; no equivalent part exists for the 1555 at all. The known weak point is the mainspring barrel bearing. The barrel arbor turns in bores cut into the main plate and barrel bridge, and after enough decades of running those bores wear out of round, the barrel tilts, and amplitude falls away; watchmakers address it by opening the worn hole and fitting a replacement bush rather than condemning a plate or a bridge. The upper barrel bush is a stocked service part for this caliber, carried under the 1530's number 7920, which is the plainest measure of how routine the repair became.
[[File:Cal 3155 movement.webp|thumb|right|220px|Cal. 3155, engraved "3155," EmmyWatch]]
 
The most closely documented 1555 in the record sits in a steel case Rolex never catalogued. Five stainless steel Day-Dates are publicly known, none of them a listed reference, and Christie's — cataloguing the fifth — sets out the census by movement number: 0004547, 0005073, DD411420, DD14749 and DD081221, the first of them published in John Goldberger's ''100 Superlative Rolex Watches'' (Damiani, 2008). The cases carry no reference and no serial, only the Rolex signature and "Stainless Steel" stamped inside the back; the day discs are French, the hands black against silvered dials, and the provenance of every known example traces to a former Rolex watchmaker. Christie's reading is that they were workshop test pieces, some handed over on retirement and some given to the Geneva horological school. Phillips sold DD411420 in Geneva in November 2019 for CHF 100,000 and pinned down what makes it more than a case curiosity: the movement is engraved 1555 but beats at 19,800 vph, the 1556's frequency, and the retiring watchmaker who received it was the man who had developed the faster beat. A caliber caught mid-development, still wearing the old number.
 
Sources split on the jewel count. Antiquorum catalogues the movement at 25 jewels, matching the bridge signature, while Phillips's description of the prototype prints 26 — the 1556's figure. The rated number in either case leaves out jewels sitting in the calendar work, which is the usual explanation offered for the drift. Height grew to 7.03mm to house the day-disc mechanism, making this the thickest of the 1500 series, and the references it powered wore the stepped "pie-pan" dial profile through to about 1970, a dial-era marker that outlasts the caliber itself.
 
<span id="cal-1556"></span>
=== Cal. 1556 ===
[[File:Cal 1556 movement.webp|thumb|right|220px|Cal. 1556]]
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! value
|-
| type
| Automatic
|-
| jewels
| 26
|-
| frequency
| 19,800 vph (2.8 Hz)
|-
| power reserve
| 42h
|-
| escapement
| Swiss lever, 52&deg; lift angle
|-
| shock
| KIF Flector, both balance pivots
|}
 
c.1965–1977/78, 26 jewels, 19,800 vph, 42 hours, chronometer, still no quickset — a higher-frequency successor to Cal. 1555, carrying the mid-and-late 4-digit Day-Date (1803, 1804, 1806, 1807, 1811). Rolex's own 1978 Technical and Service Information manual documents the balance directly: a screwed balance with 18 screws, including two regulating screws plus two gold star-shaped Microstella screws — a screwed balance with two-screw Microstella regulation, not the later four-nut style some secondary sources describe (Rolex only moved from screw to nut-shaped Microstella components in 1983). Full balance bridge rather than a cock, rhodium-plated with perlage finishing. Hacking was added mid-production in 1972; examples built before that date do not hack, a genuine running change rather than a running fault.
 
<span id="cal-1566"></span>
=== Cal. 1566 ===
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! value
|-
| type
| Automatic
|-
| jewels
| 26
|-
| escapement
| Straight-line lever
|-
| balance
| Monometallic, free-sprung Breguet spring
|}
 
The only caliber Rolex built for a single specific case: the platinum [[Reference:1831|Day-Date 1831]], commissioned for the Shah of Iran and delivered from 1977, the heaviest production Rolex ever made at 290 grams. Antiquorum's 2013 sale of example No. 05 (case 5'086'932, CHF 206,500) catalogues the movement directly: rhodium-plated, 26 jewels, straight-line lever escapement, monometallic balance adjusted to temperature and five positions, free-sprung Breguet balance spring, Microstella regulating screws, hacking. Sources disagree on how many 1831s exist — the lot's own catalogue title says eight, other researchers say nine — and on the movement itself: one concordance assigns the reference to Cal. 1556 instead of 1566, against the auction houses that physically examined the watches. Both figures are worth keeping in view rather than resolved.
 
<span id="cal-3055"></span>
=== Cal. 3055 ===
[[File:Cal 3055 movement.webp|thumb|right|220px|Cal. 3055, period parts-catalogue illustration with day-disc]]
{| class="wikitable" style="width:280px; font-size:90%;"
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! detail
Line 2,247: Line 2,351:
|-
|-
| jewels
| jewels
| 27
| 31
|-
|-
| frequency
| frequency
Line 2,254: Line 2,358:
| power reserve
| power reserve
| 48h
| 48h
|-
| escapement
| Swiss lever
|-
|-
| balance
| balance
Line 2,262: Line 2,363:
|-
|-
| shock
| shock
| KIF
| KIF Elastor
|}
|}


1977–1988, 27 jewels, 28,800 vph, 48 hours, hacking, chronometer — the first Day-Date caliber with any quickset at all, though only for the date; the day still advances by running the hands. Swiss lever escapement, free-sprung Glucydur balance with Microstella regulation, Nivarox Breguet overcoil, KIF shock protection on both the balance and the escape wheel. It carries a balance cock rather than a bridge — the sharpest visual contrast with Cal. 3155 below, which replaces it with a full transversal bridge. Height is commonly quoted at 6.3mm, but Rolex's own parts diagram gives 7.11mm; use the latter. Sapphire-crystal era, carrying the 18038, 18048, 18078, and early 18238. The day-disc mechanism sits visibly on the dial-side plate, distinct from the rotor-side bridge finishing shown on the earlier 1055/1555/1556 generation.
Cal. 3155 replaced the 3055 in 1988 and remained in production through 2019. It added independent correction of the day, giving the Day-Date a double quickset for both calendar displays.


<span id="cal-3155"></span>
The added quickset works raised the jewel count from 27 to 31. Published height figures vary between 6.00 and 6.45mm, with no known Rolex document settling the discrepancy. As elsewhere in the 31xx family, a full bridge and larger balance wheel replaced the older balance cock.
=== Cal. 3155 ===
[[File:Cal 3155 movement.webp|thumb|right|220px|Cal. 3155, engraved "3155," EmmyWatch]]
{| class="wikitable" style="width:280px; font-size:90%;"
! detail
! value
|-
| type
| Automatic
|-
| jewels
| 31
|-
| frequency
| 28,800 vph (4 Hz)
|-
| power reserve
| 48h
|-
| balance
| Free-sprung Glucydur, Microstella
|-
| shock
| KIF Elastor
|}


1988–2019, 31 jewels, 28,800 vph, 48 hours, hacking, chronometer: adds the day quickset that Cal. 3055 lacked. Pull the crown to its first position and the same motion sets both functions in opposite directions: turn clockwise to advance the date, counterclockwise to advance the day. Cal. 3055 could only do half of that. The 27-to-31 jewel jump over the 3055 traces to a real architectural change, not just the added quickset: a full transversal balance bridge replaces the 3055's balance cock, paired with a larger balance wheel. Free-sprung Glucydur balance with Microstella, Nivarox Breguet overcoil moving to Parachrom from around 2008-10, KIF Elastor shock protection — this caliber never received the later Paraflex system. The hairspring stud attachment also changes here, from glued (3035/3055) to laser-welded. Height is commonly quoted at 6.00mm; Rolex's own parts document gives 6.45mm. The double-quickset the 18238 introduced carried the 6-digit 118238 family for three decades on the same movement.
The hairspring stud is laser-welded rather than glued as on Cals. 3035 and 3055. Parachrom arrived between 2008 and 2010 according to Grail Watch Reference, or by 2013 according to Watch Wiki. Cal. 3155 retained KIF Elastor throughout and never received Paraflex, which Rolex fitted to the Day-Date II's Cal. 3156.


<span id="cal-3156"></span>
<span id="cal-3156"></span>
Line 2,330: Line 2,407:
|}
|}


2008–2015, 31 jewels, 28,800 vph, 48 hours, hacking, double quickset, chronometer — a Cal. 3155 derivative built for the 41mm Day-Date II, with a Parachrom hairspring and Paraflex shock added, powering the 218238, 218239, 218206, and 218235. It shares its 30.97mm main plate — 2.5mm wider than the standard 28.5mm Rolex automatic, to carry an enlarged day/date wheel — with three other oversized calibers: 3132, 3136, and 3187, all built to push the date window outward in an enlarged case. Most published specs list this caliber at the standard 28.5mm, an error worth correcting on sight; the wider figure comes from Stephen Foskett's Grail Watch Reference movement database, which reads the extra flange straight off Rolex's own promotional movement photography.
Cal. 3156 is a widened Cal. 3155 derivative built for the 41mm Day-Date II from 2008 to 2015. It adds a Parachrom hairspring and Paraflex protection and powers the refs. 218238, 218239, 218206 and 218235. Its 30.97mm main plate carries the enlarged calendar wheels needed to move the date window outward. The same wider format appears on Cals. 3132, 3136 and 3187. Published specifications often give the standard 28.5mm width, but Rolex's promotional photography shows the additional flange recorded by Stephen Foskett's Grail Watch Reference.


The oversizing is confined to the plate-and-bridge layer, which is why the wrong number survives so easily. Pull a parts list for a 3156 and almost every entry carries a Cal. 3135 number — escape wheel 410, pallets 421, pallet staff 419, balance staff 429, barrel arbor 307, mainspring 311, and the whole keyless and date group — identical to what a 3155 takes. The running train and escapement of a 3156 are ordinary 31xx components dropped into a wider frame. What does not cross over is structural: trade parts listings put the barrel bridge numbered to the 3156 in a fitment group with the 3132, 3136 and 3187 rather than with the 3155, weaker evidence than a factory document but consistent with the plate width.
Only the plate-and-bridge layer is oversized. The running train, escapement, keyless works and date mechanism use standard 31xx-family components, while structural parts such as the barrel bridge are shared with the wider Cals. 3132, 3136 and 3187 rather than the 3155.


The oscillator is the 3155's, and Rolex describes it in its own terms: a large balance wheel with variable inertia regulated by gold Microstella nuts rather than an index, a Breguet overcoil, and a height-adjustable traversing bridge spanning the balance in place of a cock. Free-sprung regulation means the rate is changed by shifting mass on the balance rim, and the height-adjustable bridge lets a watchmaker set endshake without shimming, which is why Rolex ties that bridge to shock resistance rather than to timekeeping in its own copy. The escapement below it is the conventional Swiss lever the 31xx family had run since 1988. What replaced the 3156 makes the point: Cal. 3255 arrived in 2015 with the Chronergy escapement, a redrawn geometry in paramagnetic nickel-phosphorus that Rolex credits with a 15 per cent efficiency gain and with roughly half of the jump from 48 to 70 hours of reserve. The 3156 belongs to the last generation before that change, with the ferrous escape wheel and pallet fork Chronergy displaced.
The oscillator comes from Cal. 3155: a large free-sprung balance with gold Microstella nuts, a Breguet overcoil and a height-adjustable transversal bridge. Below it is the conventional Swiss lever escapement used across the 31xx family. Its 2015 successor, Cal. 3255, introduced the paramagnetic nickel-phosphorus Chronergy escapement. Rolex credits that design with a 15 per cent efficiency gain and about half of the increase from 48 to 70 hours of power reserve.


Paraflex is the one component that genuinely separates this caliber from the 3155, which kept KIF Elastor to the end of its run. Rolex filed the design on 23 March 2005 under Michel Kohler and Romain Voirol, and the European patent granted on 14 May 2008, the year the Day-Date II launched. The claim describes a shock spring tied to the bearing body by four connecting arms arranged as two suspension elements either side of a central support, against the two-armed springs the trade had used for decades. The patent's own background is unusually candid about why nobody had been working on the problem: it counts roughly 400 patents on balance-staff shock bearings, 250 of them between the early 1930s and the late 1950s, and states that the solutions then in use were broadly satisfactory, which is why the subject had almost stopped attracting new development. Rolex went back to it anyway. The published gain is up to 50 per cent more shock absorption than the KIF system it replaced — a manufacturer figure with no independent test behind it.
Cal. 3156 uses Paraflex shock protection; Cal. 3155 retains KIF Elastor. Rolex filed the design in 2005, and the European patent was granted in 2008. Its spring connects to the bearing body through four arms arranged around a central support, replacing the two-arm layout common to earlier systems. Rolex claims up to 50 per cent greater shock absorption than KIF, but no independent test is cited.


This is the only Day-Date caliber whose life was bounded by a single case size. Rolex retired the Day-Date II in 2015 and replaced it with the 40mm Day-Date on Cal. 3255, while the 3155 this movement derived from carried on in the 36mm until 2019 — the derivative died four years ahead of its own base. The timing cost it one more thing: Rolex tightened the Superlative Chronometer rating to −2/+2 seconds a day in 2015, so the 3156 ran almost its entire life under the older COSC −4/+6 standard.
Cal. 3156 was confined to the 41mm Day-Date II. Rolex retired both in 2015, replacing them with the 40mm Day-Date and Cal. 3255, while the 36mm Cal. 3155 remained in production until 2019. Most Cal. 3156 watches carried the COSC −4/+6 seconds-per-day standard. Rolex adopted its −2/+2 rating in the caliber's final year, 2015.


<span id="oysterquartz-family"></span>
<span id="oysterquartz-family"></span>
== Oysterquartz ==
== Oysterquartz ==


The Oysterquartz sits outside the mechanical line entirely: Rolex's own in-house quartz calibers, launched in 1977 and run through 2001, with total output staying small — under about 25,000 watches across the full 24-year production span. Their origin traces to a genuine industry crisis: by the late 1960s Japanese quartz technology, Seiko's above all, threatened to make Swiss mechanical watchmaking obsolete almost overnight, and Rolex joined a consortium of Swiss manufacturers called the Centre Electronique Horloger (CEH) to develop a shared response. That collaboration produced the Beta 21, which powered Rolex's first quartz watch, the 1970 reference 5100 — a movement Rolex never fully embraced, since the Beta 21 architecture wouldn't fit a proper Oyster case and the 5100 shipped merely water-resistant rather than waterproof. Rolex left the CEH consortium in 1972 and spent five years developing its own quartz architecture in-house, releasing the results as cal. 5035 and 5055 in 1977, built from scratch rather than a rebadged Beta 21.
Rolex produced fewer than about 25,000 Oysterquartz watches between 1977 and 2001. The line followed the Beta 21-powered ref. 5100 of 1970, developed through the Centre Electronique Horloger consortium. The Beta 21 would not fit an Oyster case, and the ref. 5100 was water-resistant rather than waterproof. Rolex left the consortium in 1972 and spent five years developing Cals. 5035 and 5055 in-house.


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1977–2001, 11 jewels, hacking, quickset, chronometer, running on a single 32,768 Hz quartz crystal and a 1.55V silver-oxide cell — powers the Oysterquartz Datejust and Oyster Perpetual references, including the 17000, 17013, and 17014. Rolex's own service literature gives an overall diameter of 29.75mm, a case-fitting diameter of 29.00mm, and a height of 6.35mm, and describes the date mechanism as identical in principle to the mechanical Cal. 3035 that launched the same year.
Cal. 5035 powered Oysterquartz Datejust and Oyster Perpetual references, including the 17000, 17013 and 17014, from 1977 to 2001. Its date mechanism follows the same principle as the mechanical Cal. 3035 introduced in the same year.


Despite the popular "stepper motor" description, the drive is closer to an anchor escapement in miniature, and the factory documentation calls the assembly exactly that. Rolex's own term is a mobile-frame step-by-step motor, and what separates it from a conventional quartz stepper is that the coil moves while the magnets stay fixed, the reverse of the usual arrangement. Once a second the coil, carried on a rocking frame between the permanent magnets and the core, takes a single polarised pulse of 9.8 milliseconds and swings 45 degrees, alternating direction each beat. A finger fixed to that frame drives a pallet fork, and the fork drives the second wheel carrying the seconds hand directly at one beat per second, with the hour and minute hands geared off the same train. Movable pins on the fork lock the wheel between pulses, and a small magnet on the finger holds the fork against its banking until the next impulse arrives. The audible tick is the pallet engaging the wheel, which is why the sound reads as mechanical rather than as the hum of an ordinary quartz watch.
Rolex calls the drive a mobile-frame step-by-step motor. Unlike a conventional quartz stepper, its coil moves while the magnets remain fixed. A polarised pulse swings the coil frame once per second, and a finger on the frame drives a pallet fork connected directly to the seconds wheel. The pallet locks the wheel between pulses. Its audible tick comes from that engagement and sounds closer to a mechanical escapement than a conventional quartz motor.


The electronic module carries a C-MOS integrated circuit doing three jobs: the oscillator that sets the standard frequency in concert with the quartz and the trimmer, the binary divider that reduces 32,768 Hz to one pulse per second, and the impulse amplifier to whose terminals the motor connects. Rate is adjusted at service through a trimmer on the circuit board, turned with a dedicated Rolex screwdriver (tool ref. 2023) over a total range of about 2 seconds a day. The progression is not linear, the correction reverses once the maximum fast or slow point is passed, and a watch needing more than the trimmer can give needs a new module rather than more turns of the screw. Frequency is set to ±0.05 s/d at around 28°C.
The C-MOS module contains the oscillator, a binary divider that reduces 32,768 Hz to one pulse per second, and the motor's impulse amplifier. A trimmer provides a total adjustment range of about two seconds per day. Rolex specified regulation to ±0.05 seconds per day at about 28°C.


How the caliber handles temperature is unsettled. Secondary accounts describe the module as a thermocompensated oscillator, a VCTCXO with a thermistor reading ambient temperature and trimming the crystal's rate to suit, and the description is repeated widely enough to have become standard. Rolex's technical information for the two calibers never mentions compensation or a thermistor across its 32 pages. It prints an uncompensated parabolic rate curve instead, puts the quartz inversion point at 26 ±2°C, and instructs that movements be adjusted to the roughly 28°C of a watch on the wrist, with the rate falling away on either side of that point. The document may predate a later revision, but nothing in it supports the thermistor account, and the two have not been reconciled.
Temperature compensation remains uncertain. Secondary accounts describe a thermocompensated oscillator with a thermistor, but Rolex's technical document mentions neither. It instead shows a parabolic rate curve with an inversion point at 26 ±2°C and specifies adjustment near the 28°C temperature of a worn watch. The document may predate a later revision, but it does not support the usual thermistor claim.


Rolex did publish an accuracy figure, and it sits below the numbers usually quoted for these calibers: a gain or loss of less than one minute after a year of normal wear. Battery service life is given as over 24 months, with the whole movement drawing 9 microamps at most and the electronics alone accounting for no more than 3 of those. There is no end-of-life indication of any kind, so a dying cell announces itself through erratic running. Pulling the crown to the second catch cuts current to the motor entirely, which is why the factory instruction is to store these watches with the crown out, and why the seconds hand restarts exactly one second after the crown is pushed home.
Rolex specified accuracy within one minute per year under normal wear and battery life beyond 24 months. The movement draws no more than 9 microamps, of which the electronics use at most 3. There is no battery end-of-life indication; erratic running is the warning. Hacking cuts current to the motor, and the seconds hand restarts one second after the crown returns to its running position.


Service practice is unusually prescriptive. The electronic module, motor, printed circuit, battery bridle, battery, and date indicator are all barred from the cleaning baths, and the module is never to be washed or handled, since the oscillator and divider draw little enough current that contamination on the quartz-circuit connections alone can stop the watch. The motor's mobile-frame pivots are deliberately left dry, and its components were never sold separately, so a failed motor is replaced whole rather than repaired. Coil resistance is the test that separates a dead motor from a dead circuit, with 1,200 to 1,500 ohms the factory band.
The electronic module and motor are sensitive to contamination, and the mobile-frame pivots run dry. Rolex supplied the motor only as a complete unit rather than as separate components.


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1977–2001, 11 jewels, hacking, quickset, chronometer — the Day-Date counterpart to Cal. 5035, introduced in Rolex's own literature as a caliber derived from the 5035 whose calendar works on the same principle as the mechanical Cal. 3055. Everything in the 5035 entry about the mobile-frame motor, the C-MOS module, the trimmer and the current draw applies here unchanged, the two calibers sharing the same electronic module and the same motor as service parts. The difference is height: both measure 29.75mm across with a 29.00mm case-fitting diameter, but the 5055 stands 7.11mm tall against the 5035's 6.35mm, the extra 0.76mm going to the day-disc stack, mirroring the way the mechanical 3055 sits taller than the 3035 for the same reason.
Cal. 5055 is the Day-Date counterpart to Cal. 5035. The two share their motor and electronic module, while the 5055's calendar follows the principle of the mechanical Cal. 3055. Its day-disc stack increases the height from 6.35 to 7.11mm.


Unlike the 5035, the 5055 was COSC-certified from its 1977 launch — the 5035 only reached COSC around 1978-80, alongside a change to a tuning-fork-shaped quartz crystal, so early Oysterquartz Datejust dials lack "Superlative Chronometer Officially Certified" wording that contemporary Day-Dates already carried.
Cal. 5055 was COSC-certified from its 1977 launch. Cal. 5035 gained certification around 1978–80, alongside a change to a tuning-fork-shaped quartz crystal, so early Oysterquartz Datejust dials lack the "Superlative Chronometer Officially Certified" text found on contemporary Day-Dates.


The calendar side is where the 5055 takes on work of its own, and the factory service instructions are correspondingly fussier. Hour-wheel endshake must not exceed 0.03mm, held there by a set of four hour-wheel seats supplied in 0.02, 0.03, 0.04 and 0.05mm thicknesses. Both indicators have to fall freely when the movement is turned over, and an imperfect change is corrected at the jumper rather than the disc: strengthen the jumper's tension if an indicator overshoots, reduce it if the indicator falls short. Hands go on so that day and date change at midnight, to a tolerance of minus one to plus two minutes. Language changes were a service-counter job rather than a factory one, the day disc lifting out as its own part with a dedicated Rolex reamer for opening the centre hole when a replacement sits tight, which is how a Day-Date could be moved between the many day languages Rolex printed without disturbing the movement proper.
Cal. 5055 adds the day mechanism and its stricter tolerances. Rolex specified hour-wheel endshake below 0.03mm and calendar change within two minutes of midnight. The day disc is a separate replaceable part, allowing the display language to be changed without altering the movement.


Rolex's planned second-generation Oysterquartz calibers, 5235/5255 with a true stepper motor and 5335/5355 with a perpetual calendar, were both cancelled and never shipped in any watch. It powers the Oysterquartz Day-Date 19018 in yellow gold and 19019 in white gold, plus the pyramid-bezel 19028.
Cal. 5055 powers the yellow-gold ref. 19018, white-gold ref. 19019 and pyramid-bezel ref. 19028. Planned successors, Cals. 5235/5255 with a conventional stepper motor and 5335/5355 with a perpetual calendar, were cancelled before production.


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== Related but not Rolex ==
== Related but not Rolex ==


Two commonly-confused calibers turn up in Prince and Bubbleback research but aren't Rolex movements at all. Gruen's Cal. 877, used in the Techni-Quadron, is the Aegler architectural sibling of Cal. 300 sold under Gruen's own brand for the US market — the shared supplier explains the identical layout, but it was never a Rolex commercial number. And any Bubbleback-era "9¾ ligne" or "9¾ lignes" note on a reference page means only that the movement's size class was documented, not the specific caliber number — a real gap in the source, not a claim that a distinct "9¾ ligne caliber" exists as its own entry.
Gruen Cal. 877 and the Bubbleback-era "9¾ ligne" description are often misidentified as Rolex calibers. Gruen's Cal. 877, used in the Techni-Quadron, is an Aegler-built architectural sibling of Cal. 300 sold under Gruen's name in the United States. It was never a Rolex commercial number. A Bubbleback-era "9¾ ligne" description records only the movement's size class, not a distinct caliber designation.


== Sources ==
== Sources ==

Latest revision as of 04:02, 18 August 2026


Main Page -> Movements

Quick jump

Prince (shaped): 300 · 7½ T.S. 300 · 310 · 360 HW · 350 T.S.
Bubbleback / early automatic: 520 · 620 · 600 · A260 · A296 · 645 · 740 · 745
Oyster / Oysterdate Precision: 1210 · 1215 · 1220 · 1225
Vintage sport (1950s–80s): 1030 · 1035 · 1530 · 1560 · 1570 · 1575
Modern sport (1988–2020): 3035 · 3130 · 3135 · 3185 · 3186 · 3187
Milgauss: 1580 · 3131
Daytona chronograph: 72 · 727 · 4030 · 4130
Day-Date: 1055 · 1555 · 1566 · 3055 · 3155
Oysterquartz: 5035 · 5055

Rolex movements

This page covers calibers used by Rolex families in the wiki, including several numbers with no confirmed fitment. Reference pages document individual applications.

The caliber number is engraved on the movement itself and read with the caseback off; it is separate from the case serial, which is the number that dates the watch on the serial-number page. Where a movement number and case number diverge sharply, as on the stockpiled Prince calibers, the movement was made well before the case it sits in.

Aegler in Bienne made most of the mechanical movements covered here. The firm supplied Rolex as an independent manufacturer before becoming its subsidiary in 2004. Aegler also manufactured calibers based on outside designs, including the Valjoux- and Zenith-based chronographs.

Several component technologies recur across the range. Glucydur balances, standard on Rolex automatics from the 1930s onward, use a beryllium-bronze alloy that resists magnetism and temperature-driven rate variation better than the steel balances it replaced. The name combines "glucinium," an old name for beryllium, with "dur," meaning hard. Kif shock protection, made by the Vallée de Joux firm founded in 1944, cushions the balance-staff pivots with a spring-loaded free-bearing jewel setting. Rolex used the Kif system under the names "Kif Ultraflex" and "Kif Elastor." Introduced in 2000, Parachrom is Rolex's niobium-zirconium-oxygen hairspring alloy. A blue oxide coating distinguished it from around 2005; Rolex rates it as about ten times more resistant to shock than the Nivarox alloys it replaced, as well as largely immune to magnetism and temperature changes.

Prince (shaped movements)

The Prince family uses Aegler shaped movements, older than every other Rolex caliber on this page. Wilsdorf and Aegler patented the layout in 1927 as a "shaped watch movement with a seconds dial." It placed the winding barrel at one end of the rectangular movement and the balance at the other, leaving room for a larger balance wheel and mainspring barrel than rival shaped calibers of the period. The larger balance improved precision, while the larger barrel extended the power reserve.

Aegler remained an independent supplier until Rolex bought the company from the Borer family in April 2004. "Aegler" and "Rebberg" refer to the same firm; Rebberg was the street in Bienne where it stood. Aegler also made movements for Gruen. The architectural sibling of Cal. 300 sold in the United States as the Gruen Techni-Quadron, designated Cal. 877. Gruen-stamped movements sometimes appear in Rolex Prince cases, but Cal. 877 was never a Rolex caliber number.

Prince grades run Prima → Extra Prima → Ultra Prima, with higher jewel counts, more adjustment positions, and stricter chronometer testing. Only Extra Prima and Ultra Prima watches carry "Chronometer" or "Observatory" dial marks. Rolex submitted Prince movements to the National Physical Laboratory at Kew for rate certificates independent of the Swiss Bureaux Officiels Suisse de Contrôle. Its often-cited 1914 Class A Kew certificate belongs to an earlier ladies' wristwatch movement, while Prince testing at Kew-Teddington began in 1928.

Cal. 300

Cal. 300, Extra Prima grade, rectangular Prince architecture, Bonhams lot photo
detail value
type Manual
jewels 15 (Prima) · 18 (Extra/Ultra Prima)
frequency 18,000 vph (2.5 Hz)
power reserve ~50h
size 7½ × 14½ lignes / 16.9 × 32.7mm
escapement Lateral lever
shock None

Cal. 300 is the original Prince movement, made from 1928 to 1935. Rolex's factory caliber table places it under the "T.S." size code shared by Cal. 310 and Cal. 350. Christie's describes all three as the same movement base, with interchangeable parts and the balance bridge identifying the original execution. Prima movements have 15 jewels and six-position adjustment; Extra Prima and Ultra Prima versions have 18 jewels, six-position adjustment, and sometimes a Chronometer marking. David Boettcher identifies the additional jewels as two end-stones on the escape-wheel pivots and a top bearing on the centre wheel. Early movements carry the grade wording on the ratchet wheel, while later examples place it on the main train bridge. The photographed Extra Prima, marked "Observatory 6 Positions," shows the later convention.

Balance metallurgy changed gradually. Examples from 1928 use a bimetallic balance with a plain Breguet spring; by the mid-to-late 1930s, documented movements have both monometallic and bimetallic balances paired with Elinvar-alloy hairsprings. No exact transition year is established. "Patented Superbalance" on later ratchet wheels and bridges refers to Aegler's Swiss patent CH196706, filed in August 1936 and granted in March 1938. A movement carrying the mark postdates the grant. The recessed timing screws are often said to reduce air resistance, but Boettcher reads the patent as a way to maximize the balance's radius of gyration within the available space.

Cal. 300 has no shock protection, consistent with Incabloc reaching production only in 1938, after the core Prince design was established. Its winding-stem bridge is a known service weak point. A movement that sets the time and then disengages may have a broken bridge; watchmakers use aftermarket CNC-machined brass bridges and stems for this repair.

Several UK auction catalogues treat the three- and four-digit numbers found on movements in refs 1862, 1490, and 1855 as calibers. The documented numbers are 510, 579, 841, 1004, 1130, and 1439, with weaker evidence for 701 and a single record of 1759. They are almost certainly movement serials read from the plate. Continental catalogues identify the same movement class by grade and the T.S. size code instead. Cal. 414 and Cal. 527 have no documented connection to the Rolex Prince. The number 971A is a case reference, not a caliber; Antiquorum catalogued a 971A in 1989 with the same T.S./300-family movement.

Cal. 7½′′′ T.S. 300

Cal. 7½′′′ T.S. 300, marked "Rolex World's Records," "Rolex Chronometer," "18 Rubies, Ultra Prima"
detail value
type Manual
frequency 18,000 vph (2.5 Hz)
power reserve ~50h
size 7½′′′ rectangular
escapement Lateral lever
balance Monometallic
regulator Micrometer

"T.S." is Rolex's size-family code for this 16.9 × 32.7mm architecture, catalogued by Christie's as "cal. T.S. Ref. 300." There is no support for the common expansion "Très Soigné." The six-position Ultra Prima execution ran from 1932 to 1938 with a lateral lever escapement, monometallic balance, micrometer regulator, Breguet overcoil hairspring, and rhodium plating. On the 1527 Railway, Extra Prima movements outnumber Ultra Prima examples, reversing the pattern seen on the 1490. An eight-position Ultra Prima marked "Officially Tested in Eight Ways" is documented on a 1931 bamboo-bracelet example sold by Mondani in 2006.

Cal. 310

detail value
type Manual
jewels 18
size 7½′′′ rectangular (19 × 49mm cased)
escapement Lateral lever
balance Superbalance, 6-position
regulator Micrometer

Cal. 310 is the centre-seconds member of the T.S. family, used in the wedge-shaped 3361 Aerodynamic, 3362, and 3937 Prince group. Antiquorum described a 3361 in 2000 as a rhodium-plated 7½-ligne movement with 18 jewels, lateral lever escapement, six-position Superbalance, self-compensating Breguet balance spring, and micrometer regulator, in a 19 × 49mm case. That catalogue does not print the number 310, so the caliber attribution is less secure than the architecture and specifications. Movement production ended in 1938, but Aegler stock remained in Rolex cases through 1952. A 1952 example with a movement number far below its case number illustrates this stockpile pattern.

Cal. 360 HW

Cal. 360 HW, marked "Rolex, 15 Rubies, Swiss Made"
detail value
type Manual
jewels 15–18

The architecture of Cal. 360 is disputed. Christie's describes a 1938 ref. 2835 "Prince Elegant" with a tonneau-shaped 15-jewel movement, and Charles Jarman's The Rolex Reference Guide (4th edition) calls Cal. 360 a manual, small-seconds, tonneau-shaped movement with a SuperBalance. Rolex's factory caliber table instead lists a rectangular 18-jewel Basic Caliber measuring 18 × 27mm, smaller than the Cal. 300 family's 16.9 × 32.7mm.

Both Jarman and the factory table date its introduction to 1937. The disagreement concerns its shape, size, and relationship to Cal. 300. The popular claim that "HW" means Hans Wilsdorf has no independent support; the factory table appears to give the size code as "F-LW," possibly an OCR rendering related to the "F" size-family code used for Cal. 180. Shigeharu Aritake's Rolex Scene 1913–1997 is cited for a progression in which SuperBalance wording disappears from the winding wheel around 1938, but this does not resolve the architecture. Escapement and balance details remain unconfirmed.

Numbered Prince movements (510, 579, 701, 841, 1004, 1130, 1439)

Seven numbers circulate as Prince "calibers": 510, 579, 701, 841, 1004, 1130, and 1439. All are most likely movement serial numbers misread as caliber designations, so they are grouped here.

Photographed Prince plates carry a grade legend, jewel count, "Swiss Made," and a bare number stamped beside the "NN RUBIES" wording, but no caliber designation. Grade legends include Prima, Extra Prima, Ultra Prima, Observatory Quality, Officially Tested in Eight Ways, Timed 6 Positions, and For All Climates. The bare number ranges from four to seven digits. Ultra Prima 18-jewel examples with otherwise matching plates carry 1260, 1439, and 1759 in that position, confirming that the stamp varies within one movement type.

Continental auction catalogues identify these movements by size code and grade, such as "cal. T.S. 300" or "7½′′′ T.S. 300, Observatory Quality." UK lots that print a "Cal." figure also give a separate case or serial number, indicating that the supposed caliber was read from the movement. The specifications also overlap: 1439 and 1759 both describe an 18-jewel Ultra Prima movement adjusted to six positions. A bare mainplate serial has likewise appeared in print as a "1240 calibre movement."

Auction descriptions use these numbers, but the available evidence identifies them as movement serials.

number documented on catalogue text notes
510 Prince Brancard ref. 1855, serial 143**, circa 1930 "17-jewel Cal.510 manual wind movement tested to 8 positions" 8-position adjustment, against the more typical 6
579 stainless steel ref. 1862, circa 1935, case No. 103 "17-jewel Cal.579 manual wind movement" (Bonhams London) single lot; the trailing "T" in some listings is absent from Bonhams' catalogue text
701 one photograph showing "ROLEX PRINCE 701" on a 1930s piece none no recorded jewel count, adjustment count, or technical description; no auction or catalogue attribution
841 ref. 1862 circa 1930, case No. 10403 "17-jewel Cal.841 manual wind" (Bonhams London; resold through Tajan in 2019, the same watch catalogued twice) a separate listing gives 15 jewels for a "Cal. 841T" on a different 1862; a caliber designation would not change jewel count
1004 ref. 1862, Glasgow import mark for 1936, serial 176** "17-jewel Cal.1004 manual wind movement tested to 8 positions" (Bonhams, December 2015) white gold bezel, fixed wire lugs, gilt brick-link bracelet
1130 9K yellow gold ref. 1490, case 30280 "cal. 1130 manual winding lever movement, 16 jewels" lowest jewel count recorded in the group
1439 Prince Chronometre ref. 1490, Glasgow import mark for 1937, serial 307** "18-jewel Cal.1439 manual wind movement timed to 6 positions" (Bonhams) same 18-jewel, 6-position Ultra Prima specification as Cal. 1759 below

Cal. 1759 is the same phenomenon. It remains separate because the photographed watch preserves matching movement and caseback markings, but the number appears in the serial position on an Ultra Prima plate and is documented in only one regional UK auction.

Cal. 1759

Cal. 1759, "1759, 18 RUBIES, ULTRA PRIMA," with its matching case back
detail value
type Manual
jewels 18

This circa 1937 Ultra Prima Chronometer has 18 jewels and six-position adjustment. Gardiner Houlgate catalogued it in a 9ct ref. 1862 with 1937 Glasgow import hallmarks as a "cal. 1759 Ultra Prima Chronometer 18 jewel movement timed 6 positions." The photographed example retains its matching caseback, engraved "1759, 18 Rubies, Ultra Prima" alongside "31 Records Universels" and a retailer stamp. The identification rests on this single regional UK auction lot.

Cal. 350 T.S.

Cal. 350 T.S., Extra Prima grade, 15 rubies, timed to 6 positions, in a ref. 1491 jumping hour
detail value
type Manual
jewels 15 or 18 (documented both ways)
size 16.9 × 32.7mm (T.S.)
escapement Lateral lever
balance Monometallic

Cal. 350 is the jump-hour member of the T.S. family, alongside the small-seconds Cal. 300 and centre-seconds Cal. 310. Christie's and Sotheby's catalogue it in the 1491 Brancard Jumping Hour as an 18-jewel, chronometer-rated movement on the T.S. base. Another 1491 has a 15-jewel Extra Prima movement; Ultra Prima examples have 18 jewels. Jewel count varies with grade. The jump-hour disc works on much the same principle as the later Datejust date disc. Surviving examples carry Glasgow import hallmarks from 1930–31, consistent with the T.S. base's 1928–35 production window.

The 1491 case is deeper than the 1490 to accommodate the jump-hour module. Case depth distinguishes a genuine 1491 from a 1490 fitted with a later module. Known service faults include a weak jump-impulse spring that causes a "lazy" disc advance, a worn retention pawl that makes the hour disc jitter, and a misaligned dial aperture that exposes parts of two numerals.

Bubbleback and early automatic

Bubbleback and early Oyster Perpetual references use a distinct family of self-winding calibers. They followed the Prince's manual shaped movements and preceded the standardized post-war automatic line. The "bubble" refers to the domed caseback needed to clear the full-rotor automatic mechanism. It was not a bumper system, although many competing automatics still used one.

Cal. 520

detail value
type Automatic
jewels 19
frequency 18,000 vph (2.5 Hz)
escapement Straight-line lever
balance Superbalance

Cal. 520 debuted in the original 1933 ref. 1858 with its three-piece Oyster case. Antiquorum describes the 8¾-ligne rhodium-plated movement in a 3353 as automatic, with 19 jewels, 18,000 vph, a straight-line lever escapement, and a Superbalance with Breguet balance spring. Cal. 620 superseded it as the architecture developed through the mid-1930s. No confirmed movement photograph is available; a generic early Bubbleback movement should not be identified as a 520 unless the engraved caliber number is visible.

Cal. 620

Cal. 620, EmmyWatch
detail value
type Automatic
jewels 17
frequency 18,000 vph (2.5 Hz)
power reserve 35h
size 11½ lignes / 26.4mm × 7.5mm
escapement Straight-line lever
balance Superbalance (monometallic)

Derived from the manual Cal. 600, Cal. 620 became the base for Rolex's early full-rotor automatic family. Antiquorum catalogues individual examples with 17 to 20 jewels, against the table's 17-jewel specification. Earlier 1940s movements have a swan-neck micrometer regulator without shock protection; by the early 1950s, an index regulator and shock absorber appear.

Its defining feature is a unidirectional "Perpetual" rotor that turns through 360 degrees without bumpers or buffers. The rotor is engraved "ROLEX PERPETUAL / CHRONOMETER / SWISS MADE / PATENTED / SUPER-BALANCE," while the three-screw, 18mm cover plate reads "VIS TIRETTE / PATENTED / TRIGGER SCREW." Cal. 620 powered the original 1931 "Perpetual" and early Bubblebacks. Cal. 630 and the related 635 and 645 developed from the same architecture.

Cal. 630

Cal. 630, EmmyWatch
detail value
type Automatic
jewels 17
frequency 18,000 vph (2.5 Hz)
size 26.0mm
escapement Straight-line lever
balance Monometallic

Launched in 1937, Cal. 630 was chronometer-certified under the period Swiss testing system, adjusted to seven positions, and fitted with a Breguet hairspring. One secondary source gives 18 jewels rather than the table's 17. The movement developed directly from Cal. 620 and shares its "Vis Tirette *** Patented *** Trigger Screw" cover-plate marking. Its rotor and bridge also carry the same "Rolex Perpetual Chronometer, Swiss Made, Patented, Super-Balance" signature. The caliber number stamped in the small box on the bridge distinguishes the two.

Cal. 10½ Hunter

Cal. 700, the 10½-ligne Hunter, monometallic Superbalance, shown in its Oyster case
detail value
type Manual
jewels 17–18
frequency 18,000 vph (2.5 Hz)
size 10½ lignes
escapement Straight-line lever
balance Superbalance, 6-position
regulator Swan-neck micrometer

This Aegler-supplied 10½-ligne hand-wound family uses the 700/710 architecture. It has a straight-line lever escapement, monometallic Superbalance adjusted to six positions, self-compensating Breguet balance spring, and swan-neck micrometer regulator, with no documented shock protection. The movement powers the original Air-King 4925 and its Air-Lion, Air-Tiger, and Air-Giant siblings, including the sub-seconds 4365, mid-size 4444, and 4647 Hunter Precision. Its architecture links the pre-war Prince and Bubbleback movements with the post-war automatic Cal. 1030. Rolex's factory caliber table dates Cal. 700 and 710 to 1938. It lists Cal. 720 separately as an automatic movement with shock protection, not as a third member of this manual pair.

Cal. 600

Cal. 600, manual, Super Balance — EmmyWatch
detail value
type Manual
jewels 17
frequency Not recorded
power reserve Not recorded
size 9¾ lignes / 21.7mm
escapement Not recorded — Cal. 620 derivative is straight-line lever
balance Patented Super Balance
regulator Not recorded — Cal. 620 derivative is micrometer, later index
shock None documented

Cal. 600 sits one size class below the 10½-ligne 700/710/720 family and carries a patented Super Balance. Sotheby's catalogued the movement in the Mercedes Gleitze Oyster in November 2025 as a rhodium-finished Hunter-architecture base upgraded to Cal. 600. The late-1926 27mm case belongs to the watch Gleitze wore during her 21 October 1927 Channel swim attempt and is engraved "Miss M. Gleitze / The Companion 'Oyster.' Vindication Channel Swim. October 21st. 1927."

Rolex's factory table lists Cal. 600 as a Basic Caliber: manual wind, small seconds, 21.7mm, 17 jewels, entered in 1933 under a Hunter-patent size bracket. It is the root of the 9¾-ligne automatic branch. Cal. 620 followed in 1936, with Cal. 635, 640, and 645 descending from that line in 1950. Both the factory table and Sotheby's Gleitze catalogue give 17 jewels.

The Gleitze case carries Glasgow import marks for 1926/1927, but its movement is later. Rolex's factory table dates Cal. 600 to 1933, and the stamped Super Balance refers to Aegler's Swiss patent CH196706, filed in August 1936 and granted in March 1938. The movement is a service replacement fitted at least a decade after the 1927 swim. A mid-1970s Rolex service box accompanied the watch. The case and engraving establish the watch's historical provenance; the present movement is a later replacement.

The escapement and regulator remain undocumented. Cal. 620, its immediate derivative, uses a straight-line lever and changes from a micrometer regulator to an index regulator, but those details cannot be assigned to Cal. 600 without direct evidence. Shock protection is more likely absent: the factory table flags it on the 1950 calibers in this branch but not on Cal. 600, whose design predates Incabloc production in 1938.

Cal. A260

Cal. A260-era movement, engraved Rolex Self Winder, Jewels, Patented
detail value
type Automatic
jewels 19
frequency 18,000 vph (2.5 Hz)
power reserve 36h
size 26.4mm
escapement Straight-line lever
balance Superbalance, blued Breguet spring
shock Present (unnamed brand)

A260 powered the first Submariner references, 6204 and 6205, from 1953 to 1955. "A.260" is Rolex's size-family code for this movement class, comparable to the Prince family's "T.S." code. Its non-butterfly rotor distinguishes it from the butterfly-rotor Cal. 1030. Hodinkee traces A260 to a movement used in earlier Oyster Perpetuals and later Bubblebacks, predating its Submariner fitment.

Cal. A296

Cal. A296-era rotor component, engraved Rolex Perpetual Chronometer
detail value
type Automatic
jewels 18
frequency 18,000 vph (2.5 Hz)
power reserve 36h
size 29.5mm
escapement Straight-line lever
balance Monometallic Superbalance
regulator Index
shock Shock absorber (775-labelled lots only)

Made from 1952 to 1955, A296 powered the Big Crown 6200, early Explorers 6098, 6150 "Precision," 6298, and 6350, and early Datejusts 6104 and 6105. Its full rotor winds in one direction; it is not a bumper caliber. The 6150 and 6350 use the same movement in non-COSC and COSC forms. "A.296" is Rolex's size-family code and 775 its commercial number, so listings may use either designation for the same movement. Cal. 1030 replaced it in 1955 with bidirectional winding, a butterfly rotor, and a thinner automatic module. Phillips identifies that reduced thickness as the change that eliminated the domed Bubbleback caseback.

The movement has a straight-line lever escapement, monometallic balance, self-compensating Breguet balance spring, and index regulator. Catalogues using the commercial number 775 also specify six-position adjustment and a shock absorber, and Rolex's factory table marks ref. 775 as shock-protected. The two designations refer to the same build. The factory table also assigns A.296 to Cal. 765, showing that the size code covers more than one commercial caliber.

Christie's describes a 6150 balance as a "patented Super-balance," linking it to Aegler patent CH196706 and the recessed timing screws used on Cal. 300. Published jewel counts vary because some catalogues separate the going train from the automatic module. Figures of 18 and 19 appear for the base movement, with another two or seven assigned to the rotor module. One 6150 is described as a 19-jewel movement with a two-jewel automatic module. The factory table's figure of 18 counts the base plate alone.

Cal. 645

Cal. 645 winding bridge, engraved "Rolex Perpetual Chronometer, Super-Balance, Patented" — EmmyWatch
detail value
type Automatic
jewels 17–20
frequency 18,000 vph (2.5 Hz)
power reserve 41h
size 26.4mm
escapement Straight-line lever
balance Superbalance, timed to 6 positions
regulator Index
shock Shock absorber

Cal. 645 belongs to the Cal. 600 family and shares the A.260 size code with Cal. 635. The distinctions are functional: Cal. 630 has sweep seconds without shock protection, Cal. 635 has small seconds with shock protection, and Cal. 645 combines sweep seconds with shock protection. Cal. 645 powered the semi-Bubbleback Oyster Perpetual refs 6084, 6085, and 6284 around 1948–1953. Auction catalogues give 17 to 20 jewels, consistent with both differing counting conventions and market-specific tariff variants found elsewhere in the family.

The movement uses a straight-line lever escapement, Superbalance adjusted to six positions, shock absorber, self-compensating Breguet balance spring, and index regulator. Some catalogues use "monometallic balance timed to 6 positions" instead of Superbalance. Both terms describe a monometallic balance with recessed timing screws.

Rolex's factory table gives the lineage as Cal. 600 to 635 to 645. It places Cal. 635, 640, and 645 under the A.260 size code at 26.4mm and 18 jewels, all entered in 1950 and all shock-protected. The shock system separates this 1950 A.260 group from the 1936 Cal. 620 base.

Jewel counts also vary according to whether a catalogue includes the automatic module. Bonhams describes the related Cal. 745 as "18 jewels plus 7 rotor jewels." Its 20-jewel description of a Cal. 645 in a 6085, against the factory table's 18, does not necessarily indicate a different movement.

Cal. 740

Cal. 740 in a reference 4467 Datejust, case back removed, rotor engraved "Rolex Perpetual Chronometer, Super Balance, Vis Tirette"
detail value
type Automatic
jewels 18 base plate (26 in Antiquorum lots — see note)
frequency 18,000 vph (2.5 Hz)
power reserve Not recorded
size 29.5mm
escapement Straight-line lever
balance Superbalance, adjusted to 6 positions
regulator Index (A.295-labelled lots)
shock Not named in 740 lot text

Cal. 740 powered the original Datejust ref. 4467, introduced in 1945 with Rolex's first automatic wristwatch date mechanism. It uses the 720/730 base architecture and the A.295 size code, the earlier sibling of the A.296 group.

The 10½-ligne rhodium-plated movement has a straight-line lever escapement, Superbalance adjusted to six positions, and self-compensating Breguet balance spring. Some catalogues substitute "monometallic balance adjusted to 6 positions" for Superbalance, as they do for Cal. 645. No Cal. 740 description names the regulator; the related A.295-coded movement in ref. 6075 uses an index regulator.

The jewel count differs by convention. Antiquorum gives 26, while Rolex's factory table gives 18; the higher figure likely includes the winding module, as Bonhams itemises the related Cal. 745 as "18 jewels plus 7 rotor jewels."

The production date remains unresolved. Rolex's factory table enters Cal. 740 in 1950 and its Cal. 720 and 730 bases in 1945, five years after the ref. 4467 launch. Early 4467s may have used a 720-series movement before Cal. 740 arrived, or the table date may be wrong. Published descriptions of surviving 4467s do not settle the sequence.

Shock protection is unconfirmed. The factory table flags it for Cal. 720 and 730 but not Cal. 740, and ref. 4467 catalogue descriptions do not mention a shock absorber. These omissions suggest an unprotected balance but do not prove it.

Cal. 745

Cal. 745, gilt rotor engraved "Rolex Perpetual Chronometer, Super Balance" — EmmyWatch
detail value
type Automatic
jewels 18 + 7 rotor
frequency 18,000 vph (2.5 Hz)
power reserve 42h
size 29.5mm
escapement Straight-line lever
balance Superbalance
regulator Index
shock Shock absorber

Cal. 745 adds a calendar to Cal. 740 and shares balance-staff and stem parts with the 700/710/720/730/740/760/765/775 family. Rolex's factory table assigns it the A.295 size code and a 1950 entry date. It is based on the 720–740 architecture; Cal. 740 has no calendar.

Bonhams describes a Cal. 745 in a ref. 6305 as rhodium-plated, with 18 jewels plus seven rotor jewels, a straight-line lever escapement, Superbalance, shock absorber, self-compensating blued-steel Breguet balance spring, and index regulator. Separating the base movement from the winding module explains why totals of 18, 25, and 26 appear for the same build. The blued-steel balance spring is also a period marker, preceding the white-metal springs seen later.

Cal. 745 appears in the Datejust "Ovettone" group. Documented examples include a circa 1955 18K yellow-gold ref. 6305, case 97602; a ref. 6105 with 1952 Glasgow import marks and movement H78230; and a circa 1955 ref. 6304 with movement 99698/H46452. Other ref. 6105 examples use A296, placing the reference across the boundary between the A.295 and A.296 groups. The claimed Cal. 745 fitment in ref. 6039 is unverified; no supporting lot description or confirmed Rolex ref. 6039 has been identified.

Oyster and Oysterdate Precision

Precision is Rolex's non-chronometer manual line, a 10½-ligne family built alongside the automatic Bubblebacks. The Oysterdate Precision 6694 remained in production through the end of the 1980s, a year beyond the hand-wound Daytona; one surviving lot includes a 1990/1991 Rolex calendar card. Rolex continued making manual-wind watches after the 6694: the Cellini Danaos used Cal. 1602 into 2008, and the chronometer-certified Cellini Prince used Cal. 7040 until about 2015. The small-seconds Cal. 1240 also carried this architecture into the platinum Cellinium 5240 and 5241. Seconds placement, date and beat rate distinguish the seven commercial numbers. Rolex's parts plates identify Cal. 1210 as the base for 1200, 1215, 1220, 1225 and 1240.

Cal. 1210

Cal. 1210 in a 1960 Oysterdate Precision ref. 6466, movement in case
detail value
type Manual
jewels 18 (factory plate) · 17 (as signed and catalogued)
frequency 18,000 vph (2.5 Hz)
power reserve ~58h
size 10½′′′ / Ø23.80mm × 4.27mm height
escapement Straight-line lever, jewelled pallet fork
balance Glucydur, screwed rim, Breguet overcoil
regulator Index with movable stud support
shock KIF-pattern, balance and escape wheel

Rolex's parts plates identify Cal. 1210 as the family's architectural base and file the small-seconds 1200 as a derivative. The parts plates support Horbiter's identification of Cal. 1210 as the base; Fratello names Cal. 1200.

The jewel count remains unclear. Rolex specifies 18 jewels for the two no-date calibers and 17 for the date versions, yet known movements are signed "Seventeen Jewels" and major-house catalogues consistently give 17. Both counts are documented, but their distribution among watches has not been established. Contemporary American import duties taxed jewel count and also account for the "UNADJUSTED" stamps found on some movements.

The balance is Glucydur with a Breguet overcoil, as specified on the sibling Cal. 1200 plate. Regulation uses a conventional index and movable stud, with adjusting washers in five thicknesses. It is not free-sprung; Rolex reserved Microstella for its 12½-ligne chronometers.

The pallet fork runs in jewels, while the escape wheel has shock-mounted settings and cap jewels on both pivots, matching the treatment of the balance. Indirect centre seconds, driven from the fourth wheel through a friction-sprung pinion, can produce seconds-hand flutter even in a healthy movement. The earliest examples may lack shock protection; Antiquorum's 1946 ref. 4560 description names none.

Documented fitments include refs. 3745, 4560, 6420, 6422, 6426/6427, 6466, 6480, 6482, 6494, 9083 and 9659. Bonhams also records a ref. 6694 with a III.60 caseback date on Cal. 1210. Ref. 6082 is disputed: Crott assigns one example to 1210, while Antiquorum and EveryWatch catalogue the reference with Cal. 710.

Cal. 1215

Cal. 1215 in a movement holder, from a 1962 Oyster Date Precision ref. 6694 service
detail value
type Manual
jewels 17
frequency 18,000 vph (2.5 Hz)
power reserve ~58h
size 10½′′′ / Ø23.80mm × 5.07mm height
escapement Straight-line lever
balance Glucydur, Breguet overcoil (via base 1210) · flat in one lot
regulator Index with movable stud support
shock KIF-pattern
date Non-quickset, dragging change

Cal. 1215 adds a calendar to the 1210, increasing movement height from 4.27mm to 5.07mm. Its two-page parts sheet covers only the calendar mechanism and defers the rest to Cal. 1210. Date discs came in champagne, silvered, and champagne with red-and-black printing.

The hairspring is disputed. The parts plates imply the 1210's Breguet overcoil because the 1215 sheet specifies no separate balance. Antiquorum describes one ref. 9996 with a flat hairspring and index regulator, but uses Breguet wording elsewhere. No catalogue describes the caliber as free-sprung.

The non-quickset date moves over roughly forty minutes and seats at the end of the change. A pawl on the calendar wheel engages a star wheel beneath the date disc before the jumper spring seats it. Rolex used the same arrangement in the 7xx, 1035 and 11xx families; instantaneous change arrived with the 1065/1066 and 15xx calibers. A date change beginning around 11:20 is normal for this mechanism.

Christie's places the ref. 6494 changeover between a circa-1956 example with Cal. 1210 and a circa-1958 example with 1215. Other documented fitments include the Speedking 6430, early 6694 production, and refs. 9996/9919. Refs. 6094 and 6294 used Cal. 740 and 790 respectively, rather than 1215.

Cal. 1216

detail value
type Manual (assumed, by family)
jewels not documented
status Number attested in the parts trade only

Almost nothing is known about Cal. 1216. The common description of it as a 17-jewel Cal. 1215 variant has no traceable support.

Rolex's surviving parts plates cover 1200, 1210, 1215, 1220, 1225 and 1240, but omit 1216. No major-house lot identifies a Rolex Cal. 1216, and Heritage's apparent example is a case reference. Confusion is also possible with Ronda's contemporary 1216 movement.

The parts trade nevertheless records it as a Rolex number. Cas-Ker's genuine-parts catalogue places 1216 between 1215 and 1220 and lists crown-wheel screw 1216.5420, following Rolex's caliber-prefixed numbering convention.

The parts catalogue attests the Cal. 1216 designation. Its jewel count, seconds layout, beat rate and fitments remain unknown. Published specifications derived from the 1215 are unconfirmed.

Cal. 1220

detail value
type Manual
jewels 18 (factory plate) · 17 (as signed)
frequency 21,600 vph (3 Hz)
power reserve ~58h
size 10½′′′ / Ø23.80mm × 4.27mm height
escapement Straight-line lever
balance Screwless, inertia blocks, flat hairspring
regulator Index with movable stud support
shock KIF-pattern

Cal. 1220 raises the 1210 platform to 21,600 vph and uses a different oscillator. Both its parts plate and the 1978 third edition of Rolex's Technical and Service Information give that rate. The sometimes-published 19,800 vph figure is unsupported.

The higher-beat generation replaces the 1210's screwed Glucydur balance and Breguet overcoil with a smooth-rimmed balance and flat hairspring. Gilt and nickel-plated inertia blocks provide about ten seconds per day of fine adjustment across their range; the index handles larger corrections. Separate regulator, stud-support and regulating-stud parts confirm that this is an index-regulated movement, not a free-sprung one.

Cal. 1220 appears mainly in the oversize ref. 8029, but its dates conflict. Phillips gives 1950, Antiquorum dates case 714105 to about 1951, and Sotheby's dates that same case to about 1961 without naming its caliber. The earlier dates sit awkwardly beside the later-1960s siblings and remain unresolved. Claims that 1220 movements were commonly signed 1225, including those in later ref. 6426 production, are unverified.

Cal. 1225

Cal. 1225 in a ref. 6694 Oysterdate Precision, bridges marked "Montres Rolex S.A. Swiss"
detail value
type Manual
jewels 17
frequency 21,600 vph (3 Hz)
power reserve ~58h
size 10½′′′ / Ø23.80mm × 5.07mm height
escapement Straight-line lever
balance Screwless, inertia blocks, flat hairspring
regulator Index with movable stud support
shock KIF
date Non-quickset, dragging change

Cal. 1225 adds a calendar to the 1220 and carried the Oysterdate Precision 6694 through its final years. Rolex's plate specifies a timed flat hairspring with gilt and nickel-plated inertia blocks, consistent with Antiquorum's descriptions of refs. 6426 and 6694. Published claims of a Breguet overcoil conflict with the factory plate and auction record. Bonhams' reference to a "Gyromax balance" is a cataloguing error; Gyromax is Patek Philippe's free-sprung system.

Rolex used "Precision" on uncertified manual and automatic movements, including the Air-King 5500. On Cal. 1225, the "UNADJUSTED" stamp records an import-duty classification.

The caliber does not hack. The 1210 parts plate contains no stop lever or hack spring, and Rolex's 1978 service book covers hacking only for the late 1500 series and the 2030/2035.

Recurring service faults include worn pendant-tube and crown threads, winding stems and mainsprings, plus water-damaged date rings. The early Oysterdate calendar is the movement's weak point, though the pallet fork is fully polished and its jewels lightly undercut. Rolex service centres still accept these calibers; one 1974 example returned from overhaul running two seconds per day with a measured 57-hour reserve.

Documented fitments include refs. 6426, 6466 and, most often, 6694 from the late 1960s through at least 1979. Comparison of a 1966 ref. 6694 with Cal. 1215 and a 1973 example with 1225 places the changeover around 1967.

Cal. 1200

Cal. 1200, bridges marked "Montres Rolex S.A. Geneva Swiss, Seventeen 17 Jewels", from a Rolex Precision service
detail value
type Manual
jewels 17
frequency 18,000 vph (2.5 Hz)
power reserve ~58h
size 10½′′′ / Ø23.80mm × 3.65mm height
escapement Straight-line lever, jewelled pallet fork and staff
balance Glucydur, Breguet overcoil
regulator Index with movable stud support
shock "Rolex Shockresisting" device

Cal. 1200 is the family's small-seconds variant and, at 3.65mm, its thinnest member. Moving the seconds from the centre to a subdial requires a separate main plate and train-wheel bridge rather than an added module. The plate, bridge, third and fourth wheels, pallet fork and staff are jewelled.

The bilingual parts plate specifies Rolex's own "Shockresisting" device rather than a trade name. It lists a pivoted Glucydur balance with roller and a regulated Glucydur balance with Breguet hairspring, the 18,000-vph oscillator inherited by the 1210 and 1215.

The caliber number is engraved in the balance-wheel hub sinking rather than on a bridge or the main plate. The same document directs watchmakers to Cal. 1210 for all shared parts, confirming the family's parentage.

No major-house lot names Cal. 1200, so its fitments remain unestablished. The high-beat small-seconds Cal. 1240 is better documented in the platinum Cellinium 5240 and 5241, with a monometallic balance adjusted to four positions and a flat hairspring. That caliber kept the architecture in production for about a decade after the Oysterdate ended.

Vintage sport calibers (Submariner, GMT-Master, Explorer, Air-King)

The A-series and Cal. 1030 preceded the long-running 15xx family. Cal. 1520 became its main uncertified movement, while Cals. 1560 and 1570 supplied chronometer-rated sport references into the 1980s.

Cal. 1030

Cal. 1030, engraved "1030," 25 jewels, butterfly rotor
detail value
type Automatic
jewels 25
frequency 18,000 vph (2.5 Hz)
power reserve 42h
size 28.5mm × 5.85mm
escapement Straight-line lever
balance Monometallic, blued Breguet spring
shock KIF

Produced from 1950 to 1962, Cal. 1030 was Rolex's first bidirectional and fully in-house automatic. Its 5.85mm profile ended the domed Bubbleback caseback, while the cutaway "butterfly" rotor stamped ROLEX PERPETUAL PATENTED is its clearest visual identifier. Finishing includes perlage on the rhodium-plated main plate, brushed bridges, polished screw heads and red anodized-aluminium reversing wheels. A conventional index regulates the movement; the visible regulator arm distinguishes it from the later free-sprung 1560 and 1570. Documented fitments include ref. 6098 from 1952, Submariners 6536, 6536-1 and 6538, Explorer 6610 and Air-King 6552. The same movement appeared in chronometer and non-chronometer watches.

Cal. 1035

Cal. 1035, rotor engraved "Rolex Perpetual Patented" — EmmyWatch
detail value
type Automatic
jewels 25
frequency 18,000 vph (2.5 Hz)
power reserve 42h
size 28.5mm × 6.66mm
escapement Straight-line lever
balance Monometallic, temp + 5 positions
regulator Index (Cal. 1030 base)
shock Shock absorber

Cal. 1035 adds a date to the 1030 and appeared in 1957. It powered Oyster Perpetual Date refs. 6518, 6530 and 6534, plus the Datejust Thunderbird 6609. Rolex describes its non-quickset calendar as "progressive": the date moves gradually through the night, unlike the instant-change 1036 GMT.

The 1035 inherits the 1030's conventional index regulator. Although auction descriptions do not name the regulator, the production dates and shared base support the index arrangement.

Rolex stamped the 1035's self-winding bridge "1030," as it also did on the 1036. This causes auction catalogues to identify the same reference under both numbers. The calendar work and 6.66mm height distinguish the 1035 from the 5.85mm no-date 1030. A correct ref. 6534 contains a 1035 regardless of its bridge engraving.

Cal. 1530

Cal. 1530-era butterfly rotor halves, Rolex coronet stamped
detail value
type Automatic
jewels 17 / 25 / 26 (market variants)
frequency 18,000 vph (2.5 Hz)
power reserve 44h
size 12½′′′
escapement Swiss lever, club-tooth
balance Screwed Glucydur
regulator Index (coarse) + micro-star fine-adjust screws
shock KIF Flector

Cal. 1530 ran from 1957 to 1965. Its 17-, 25- and 26-jewel versions are concurrent market variants, not a chronological progression. Seventeen-jewel movements appear in a 1958-era ref. 5508, a 5500 and a 1011 Eaton, and Rolex's 1978 service booklet still treats low-jewel 1520 and 1530 movements as current configurations.

Cal. 1530 is the base for the 1520, 1560, 1570 and 1580. They share plates and many service parts, including interchangeable automatic-device bridges, so the engraved bridge number may not identify the movement beneath it. Balance-bridge and regulator form are more reliable. Cal. 1030, not 1530, was Rolex's first fully in-house automatic.

Regulation combines an index for coarse adjustment with two pairs of micro-star fine-adjustment screws on the outer balance rim. Turning a screw clockwise draws it inward and gains rate. The system resembles Microstella, and Horotec lists the same adjustment tool for the 1530 and later Microstella calibers, but Rolex reserved the Micro-Stella name for its free-sprung 12½-ligne chronometer movements. The 1530 retains an index.

The form-1 balance cock uses KIF Flector; forms 3 and 4 use Elastor, with form 2 also assigned to Flector by specialist comparisons. Interchangeable bridges mean an individual movement's shock setting may not match its engraved caliber number.

The hairspring remains disputed. Antiquorum consistently describes a Breguet overcoil and index regulator, while much of the reference literature gives a flat hairspring with stick regulation. Reliable sources support both descriptions.

Chronometer status also varies. Sotheby's describes the 1530 as uncertified, while Phillips and Christie's identify chronometer examples in the 5504 family. Rare 5512 and 5508 watches with four-line chronometer dials and Cal. 1530 have been reported, though no major-house lot confirms them. Certification appears to have been occasional. The Microstella-equipped 1555 and 1560 became the regular chronometer alternatives used in early refs. 1675 and 1016.

The rotor changed from butterfly to half-moon during production. Later movements also gained blued automatic-bridge screws and coloured reversing wheels in place of brass-coloured gears. Rolex describes the red wheel finish as a hardening treatment for aluminium introduced in 1957; collector descriptions often call the wheels purple and Teflon-coated. Rotor and reversing-wheel form help date an example.

The 1530 first entered the Submariner in ref. 5508, followed by 5510; neither was chronometer-rated at launch. It replaced the 10-series in non-chronometer watches, including Precision models, the Air-King, ref. 5504 "Super-Precision" Explorer and the Canadian Explorer-Date with Cal. 1535. Certified models such as the 6542 GMT, 6610 Explorer, Datejust and Day-Date retained 10xx calibers for longer. Strongly documented fitments include refs. 5508, 5510, 5512, 5513, 5500 and 5504. Single-lot support exists for 5501, 5502, 5506, 5516 and 5590/1011 Eaton. Bonhams listings for refs. 1002 and 1003 are internally inconsistent and remain unconfirmed.

Rolex specifies a 0.122–0.125mm mainspring for the 18,000-vph 1530 and 1560, against up to 0.125 or 0.128mm for the higher-beat 1520 and 1570. Early unjewelled barrel-bridge arbor holes can wear; Rolex prescribed closing the hole or reaming it for a jewel, while later production received a bushing. Rotor-axle wear is another known fault. On the 1560, a hard shock could push the hairspring into the regulator. Rolex supplied a safety pin free of charge and later made it standard, so both guarded and unguarded examples are correct.

Cal. 1520

Cal. 1520, engraved "1520," EmmyWatch
detail value
type Automatic
jewels 17 / 25 / 26
frequency 19,800 vph (2.8 Hz)
size 12½′′′
escapement Straight-line lever
balance Monometallic, screwless, flat hairspring
regulator Index (coarse) + two inertia blocks
shock KIF

Produced from 1963 to 1990, Cal. 1520 is the non-chronometer, higher-beat derivative of the 1530. Rolex pairs the 18,000-vph 1530 with the 1560, and the 19,800-vph 1520 with its certified counterpart, the 1570.

Rolex describes regulation by an index and two inertia blocks, one gilt and one nickel-plated, on a screwless balance with a flat hairspring. Turning their splits inward slows the movement and outward gains rate, with about ten seconds per day across the adjustment range. The index handles coarse changes. This differs from both the 1530's micro-star screws and the 1570's free-sprung Microstella system.

Certified calibers use free-sprung Microstella regulation; Cal. 1520 uses an index and inertia blocks.

The rim weights can be mistaken for a free-sprung system, but factory documentation confirms the regulator and inertia blocks. Two Bonhams descriptions call the 1520's balance "free-sprung Gyromax," an error that applies Patek Philippe's trademark to an index-regulated Rolex movement.

Auction descriptions consistently give a flat hairspring, apart from one 2013 Antiquorum outlier that says Breguet. Shock protection is KIF in Flector or Elastor form, identified by balance-bridge and regulator shape. That shape is more reliable than the engraved caliber number because bridges interchange across the series.

The 17-, 25- and 26-jewel counts are concurrent market variants. The 17-jewel version uses a different main plate and bridges, altered escape-wheel pivot geometry, and bushings in place of jewels in the automatic module. The going train and balance are unchanged, so jewel count does not affect timekeeping. Dated examples place 17- and 26-jewel movements together from the mid-1960s, with 25-jewel examples running alongside them.

American tariffs rose sharply above 17 jewels, but Rolex did not document this as the reason for the low-jewel version. Seventeen-jewel movements also reached Europe and Asia, so general cost reduction remains another possibility. The American presentation ref. 7002 has a rotor marked "SEVENTEEN JEWELS" and "UN" for unadjusted, both relevant to the tariff schedule, but this does not settle the question.

Documented fitments include the 5513, 5514 COMEX, 5517 military Submariner, 5500 Air-King and 5520. Ref. 1002 uses chronometer calibers 1530 or 1570; apparent 1520 examples are ref. 5500 cases with 1002 stamped inside the caseback. Ref. 5501 remains unconfirmed. Hacking arrived as a running change around 1972 through parts 8073 and 8074. Two lines above six o'clock identify the non-chronometer dial, against four on certified models.

The barrel bridge and arbor hole are known wear points. Rolex prescribed closing a worn hole or reaming it for a 2.30mm jewel; a later beryllium bushing largely solved the problem. Rotor axles and autowinder wheels also wear, and replacement parts are scarce. Gritty manual winding is normal because the reversers run without lubrication.

Cal. 1535

Cal. 1535, EmmyWatch
detail value
type Automatic
jewels 26
frequency 18,000 vph (2.5 Hz)
power reserve 42h
size 28.5mm
escapement Swiss lever
balance Monometallic, screwed
regulator Index, pre-Microstella
shock Shock-absorber

Cal. 1535 is the non-chronometer date version of the 1530, introduced in 1957 for the Air-King-Date 5700/5701. Rolex's factory caliber table places it before the later 1520-based Cal. 1525, consistent with the production dates. Monochrome likewise assigns both calibers to the 5700, with 1535 first.

Auction houses usually catalogue refs. 5700 and 5701 under the base caliber. Antiquorum assigns a 1963 ref. 5700 to Cal. 1530 and a 1972 example to 1520, though neither base movement has a date. Those entries agree with Rolex's grouping of 1535 components under Cal. 1530 and 1525 components under Cal. 1520, but they do not identify the fitted caliber.

No auction lot identifies a Cal. 1535 directly, so the listed mechanical figures come from its Cal. 1530 base. Evidence for the hairspring conflicts: auction wording gives a flat spring, while Rolex balance assembly 7855 for the 1530 uses a Breguet overcoil. Repeated catalogue boilerplate is more likely than a separate variant. The 1535 predates Microstella and uses an index with a screwed balance, consistent with the 5700's Precision grade.

Although Cal. 1530 was phased out by 1965, its 1535 date derivative remained in the Air-King-Date into the late 1980s.

Cal. 1525

Cal. 1525, EmmyWatch
detail value
type Automatic
jewels 17 / 25
frequency 19,800 vph (2.8 Hz)
power reserve 42h
size 28.5mm
escapement Swiss lever
balance Monometallic, flat hairspring
regulator Index
shock Shock-absorber

Cal. 1525 is the higher-beat, non-chronometer date version of the 1520. Introduced in 1965, it carried the Air-King-Date 5700/5701 through later production. Contemporary chronometer-rated Oyster Perpetual Date references used a related 1500-series caliber instead.

Auction catalogues often label the date-equipped Cal. 1525 as Cal. 1520. Antiquorum does so on a 1972 ref. 5700, while describing the expected flat hairspring and index-regulated architecture. The chronometer-grade 1560 and 1570 use a Breguet overcoil and Microstella. The Cal. 1525 uses the index regulation associated with the uncertified 5700.

Jewel counts of 17, 25 and 26 reflect parallel market executions. Rolex balance-assembly numbers confirm a flat hairspring for the 1520 and 1525, against a Breguet spring on the 1530 and Microstella on the 1560. The 1525 remains index-regulated.

Cal. 1560

Cal. 1560, EmmyWatch
detail value
type Automatic
jewels 26 (25 in some lot descriptions)
frequency 18,000 vph (2.5 Hz)
power reserve 42h (secondary sources only)
escapement Straight-line lever
balance Free-sprung monometallic, Microstella screws
shock KIF (pattern not named in lots)

Cal. 1560 arrived in 1959 as the chronometer-grade 15xx movement, with a free-sprung balance adjusted to temperature and five positions. Auction catalogues give both 25 and 26 jewels without establishing a pattern. Antiquorum usually describes a Breguet overcoil; its flat-hairspring description for one ref. 1502/1503 is an outlier.

Cal. 1560 uses free-sprung Microstella regulation; Cal. 1530 uses an index. Watches made from 1959 to 1965 were tested by the Bureaux Officiels de Contrôle de la Marche des Montres, usually under collective certificates and to a standard around −1/+10 seconds per day in five positions. COSC did not exist until September 1973, so describing an early 1560 as COSC-certified is anachronistic.

Factory balance 7980 is used in the 18,000-vph chronometer group: 1555, 1556, 1560 and 1565. Later replacement part 8106 and balance bridge 8102 span both 18,000- and 19,800-vph family members, so a serviced 1560 may carry the later balance. Documented fitments include the four-line 5512, 5504 and Explorer 1016. The GMT-Master 1675 instead used the 1565 to about the 1.4-million serial range and the 1575 thereafter. Family-wide bridge engravings explain 1675 movements marked 1560 or 1570; a base 1560 lacks both calendar and 24-hour works. Although 1570 became the new fitment in 1965, 1560 movements appear in Explorers until about 1967.

Cal. 1565

Cal. 1565, EmmyWatch
detail value
type Automatic
jewels 25–26 (sources disagree)
frequency 18,000 vph (2.5 Hz)
power reserve 44h
escapement Straight-line lever
balance Free-sprung, Microstella
shock KIF

Produced from 1959 to 1965, Cal. 1565 is the early ref. 1675's "caller" GMT movement: its 24-hour hand remains linked to the main hour hand rather than independently adjustable. Rolex kept that layout until Cal. 3085. The 1565 introduced a free-sprung Breguet overcoil with Microstella regulation to this lineage, replacing the index used by earlier sport calibers.

Cal. 1570

Cal. 1570, open caseback
detail value
type Automatic
jewels 26
frequency 19,800 vph (2.8 Hz)
power reserve 48h
size 12.5′′′ (28.2mm)
escapement Straight-line lever
balance Free-sprung monometallic, four Microstella screws
shock KIF (Flector or Elastor)

Cal. 1570 is the 19,800-vph revision of the 1560, introduced in 1965. It retains the free-sprung Breguet overcoil and Microstella regulation, with adjustment to temperature and five positions. Family-wide bridge engraving causes date movements such as the 1575 in a ref. 1665 to appear marked 1570; the engraving alone does not identify the exact caliber.

The balance has four Microstella screws in two opposing pairs, not two. Rolex required equal adjustment within each pair to preserve poise. The larger pair changes rate by about two seconds per day and the smaller by about one. On this family the screws sit in the balance rim; the later 3135 platform moves its Microstella nuts to the inner rim.

KIF's circa-1972 material catalogue lists Flector and Elastor settings for Rolex; it does not list Ultraflex. Auction catalogues name only a shock absorber, while Rolex part 8065 serves the upper balance setting across the 1520, 1530, 1560 and 1570. The available records support Flector and Elastor.

Hacking appeared gradually around 1971–72, with timing varying by model. Cal. 3035 began replacing the 1570 in new production from 1977, but the Explorer 1016 retained it until 1988–89. The documented diameter is 12.5 lignes, or 28.2mm; the often-published 28.5mm is a rounded conversion. Published heights conflict.

Cal. 1575

Cal. 1575, EmmyWatch
detail value
type Automatic
jewels 26 (25 per Ashton Tracy)
frequency 19,800 vph (2.8 Hz)
power reserve 48h
escapement Straight-line lever
balance Free-sprung monometallic, Microstella screws (1570 balance)
shock KIF (Flector or Elastor)

Cal. 1575 adds calendar work to the 1570; the GMT execution also adds a 24-hour train. Antiquorum and Sotheby's give 26 jewels, while watchmaker Ashton Tracy's 2018 Quill & Pad study gives 25. Tracy records a 48-hour power reserve; the often-published 50-hour figure lacks support.

Rolex engraved the 1575 bridge "1570," so that marking on a ref. 1680 or 1675 identifies the caliber family. Factory parts records distinguish 1565G, 1575, 1575G and 1575GMT. Date and GMT versions are separately catalogued builds, and the GMT parts also circulated as a conversion set for a standard 1560 or 1570.

The 1575 shares factory balance assembly 8106 with the 1570 and related family members. It has shock protection on the escape wheel on both dial and movement sides, as well as on the balance. Documented fitments include the Submariner 1680, GMT-Master 1675 from about the 1.4-million serial range, Explorer II 1655 and Sea-Dweller 1665.

GMT-Master line

Early GMT calibers synchronized both hour hands. Cal. 1036 and 1065 belong to the bakelite-bezel 6542 era. Cal. 1565, 1575, and 3075 retained that "caller" layout through the 1675 and 16750 generations. Cal. 3085 introduced an independently adjustable local-hour hand, while Cal. 3175 retained the synchronized layout in the 16700 until 1999 alongside the Cal. 3185 and 3186 used in the 16710.

Cal. 1036

Cal. 1036, EmmyWatch
detail value
type Automatic
jewels 25
frequency 18,000 vph (2.5 Hz)
power reserve 42h (secondary sources only)
escapement Straight-line lever (inferred, 1030 base)
balance Monometallic (inferred, 1030 base)
shock KIF (inferred)

Cal. 1036 is Rolex's first GMT movement, a Cal. 1030 with a 24-hour train added for the bakelite-bezel 6542. It runs at 18,000 vph and was chronometer certified. The 6542 used Cal. 1036 first, followed by 1065 and 1066 during its 1955–1959 production run. Its period chronometer certificate came from the Bureaux Officiels; COSC did not exist until 1973.

The start year remains disputed. Phillips dates the 6542's release to 1954, Hodinkee starts production in 1955, and Rolex registered the GMT-Master name on 21 April 1955. An announcement in 1954 followed by sales in 1955 would reconcile those dates, but Rolex has not documented that sequence.

The listed escapement, balance and shock protection are inferred from the Cal. 1030 base; no Cal. 1036 source documents them directly. Auction catalogues seldom identify a 6542 movement as Cal. 1036, so those three specifications remain provisional.

Cal. 1065

Cal. 1065, EmmyWatch
detail value
type Automatic
jewels 25
frequency 18,000 vph (2.5 Hz)
power reserve 42h (secondary sources only)
escapement Straight-line lever (inferred, 1030 base)
balance Monometallic (inferred, 1030 base)
shock KIF (inferred)

Cal. 1065 is the mid-run 6542 caliber. Multiple Phillips lots identify it as an automatic movement with 25 jewels, the same jewel count recorded for the Cal. 1066 that followed.

Its dates are less secure than its specification. Cal. 1065 sits second in the 6542's three-movement sequence and is generally dated to 1957, but no factory document or dated lot fixes the transition. The 42-hour power reserve is also a secondary-source figure.

The escapement, balance, and shock rows likewise derive from the Cal. 1030 base. Cal. 1066 cataloguing supports that family relationship, but these details have not been documented directly on a Cal. 1065.

Cal. 1066

Cal. 1066, stamped "1066," butterfly rotor engraved "Rolex Perpetual Patented," EmmyWatch
detail value
type Automatic
jewels 25
frequency 18,000 vph (2.5 Hz)
power reserve 42h

Cal. 1066 was the third and final movement fitted to the 6542, replacing Cal. 1065 for the last two years of production. It runs at 18,000 vph with 25 jewels and about 42 hours of reserve. Antiquorum describes a straight-line lever escapement, monometallic balance adjusted to temperature and five positions, shock absorber, and self-compensating Breguet hairspring. Its matching descriptions for Cal. 1030 and 1065 support a shared base with GMT work added.

The regulator and balance specification remain uncertain. Cal. 1030 descriptions name an index regulator, while Cal. 1066 descriptions omit it; one 6542 is catalogued with a free-sprung Glucydur balance. This may mark a running change or inconsistent cataloguing. A circa-1959 Phillips example directly confirms the Cal. 1066's butterfly rotor.

Documented examples cluster in 1958 and 1959, including a steel 6542 with a IV.1958 caseback and two gold watches dated to 1959. Rolex changed caliber numbers during the reference's run, so two outwardly similar 6542s can carry different movements.

Cal. 3075

Cal. 3075, engraved "3075," EmmyWatch
detail value
type Automatic
jewels 27
frequency 28,800 vph (4 Hz)
power reserve 48h
escapement Straight-line lever
balance Free-sprung monometallic, Microstella screws
balance support Balance cock (3035 generation)
shock KIF (inferred; lots record only "shock absorber")

Cal. 3075 carried the synchronized "caller" GMT layout into the 16750 generation. It has 27 jewels, a straight-line lever escapement, a monometallic balance adjusted to temperature and five positions, a free-sprung Breguet hairspring regulated by Microstella screws, hacking, and quickset. The quickset advances only the date wheel.

The balance is monometallic, not Glucydur. Catalogue descriptions identify Microstella screws but do not record their count, material, or position on the rim. They also name a shock absorber without identifying its maker, so the KIF attribution remains inferred from Rolex practice of the period.

The 3075 belongs to the 3035 generation and uses its cantilevered balance cock. Cal. 3175 and 3185 later introduced a balance bridge anchored at both ends. Its start date is disputed: the 16750 did not appear in a Rolex catalogue until 1981, while Antiquorum dates production of the 16758 to 1979. Known fitments are the steel 16750, steel-and-gold 16753, and gold 16758. The 3075 also moved the GMT hand above the hour hand, reversing the Cal. 1575 stack; later GMT calibers retained that arrangement.

Cal. 3085

Cal. 3085, EmmyWatch
detail value
type Automatic
jewels 27
frequency 28,800 vph (4 Hz)
power reserve 48h
size 28.5mm × 6.3–7.2mm (sources disagree)
escapement Swiss lever
balance Free-sprung, Microstella
shock KIF (per published specs, unconfirmed)

Cal. 3085 ran from 1983 to 1989 on the Cal. 3035 platform, with 27 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, and chronometer certification. It was the first Rolex caliber to separate the local-hour hand from the 24-hour hand. The crown jumps the local hour forward or backward in one-hour steps without disturbing the minutes, seconds, or home-time hand. The date advances only by cycling the local-hour hand, so the movement has no direct quickset date.

Published thickness figures conflict. Grail Watch Reference gives 6.3mm, while Caliber Corner gives 7.2mm against the Cal. 3185's 6.45mm. The 16760's thick movement and case produced the "Fat Lady" and "Sophia Loren" nicknames. Cal. 3085 appeared only in the 16760 GMT-Master II and 16550 Explorer II. Published specifications agree on a Breguet hairspring and Microstella regulation, but KIF shock protection has not been confirmed by an auction description or Rolex document.

Cal. 3175

Cal. 3175, EmmyWatch
detail value
type Automatic
jewels 31
frequency 28,800 vph (4 Hz)
power reserve 48h
escapement Swiss lever
balance Free-sprung Glucydur, Microstella
balance support Balance bridge (3135 generation)
shock KIF Elastor (3100-family text, not lot-confirmed)

Cal. 3175 ran from 1988 to 1999 with 31 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, quickset, and chronometer certification. Auction descriptions confirm the jewel count and adjustment to temperature and five positions. Published 3100-family specifications support a free-sprung Glucydur balance, Microstella regulation, Breguet hairspring and KIF Elastor setting. No examined Cal. 3175 lot confirms KIF Elastor.

Architecturally, Cal. 3175 is a Cal. 3135 with a fixed 24-hour hand. It uses the 3135's balance bridge, anchored at both ends, where Cal. 3075 used a cantilevered cock. The 24-hour hand remains linked to the local hour hand, so a second time zone is read from the rotating bezel. The 16700 kept this synchronized layout while the rest of the line moved to the jumping-hour Cal. 3185.

Cal. 3175 appeared only in the 16700 and was Rolex's last fixed GMT movement. Reports of factory Cal. 3185 fitment in late 16700s rest on a contradictory parts listing and a rebuilt watch; documented Cal. 3185 fitment belongs to the 16710. Sotheby's has incorrectly described Cal. 3175 as having an independent GMT hand. The accepted 16700 production span is 1988–1999, although Fratello gives 2001 in one account. The 1997 change from tritium to Super-LumiNova affected the dial, not the movement.

Cal. 3185

Cal. 3185, engraved "3185"
detail value
type Automatic
jewels 31
frequency 28,800 vph (4 Hz)
power reserve 48h
size 6.45mm
balance Free-sprung Glucydur, four Microstella nuts

Cal. 3185 ran from 1989 to about 2007. Derived from Cal. 3135 with added 24-hour work, it has 31 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, quickset, chronometer certification, and KIF Elastor shock protection. It powered the 16710, 16713, 16718, and 16570, replacing Cal. 3085 in the GMT-Master II and Explorer II.

The balance carries four Microstella nuts arranged as two opposing pairs of different sizes. Rolex's Microstella wrench instructions require equal adjustment of both nuts in a pair to preserve the balance-wheel poise. Adjusting one without its opposite puts the wheel out of poise.

At 6.45mm, Cal. 3185 is slimmer than the Cal. 3085 it replaced, allowing the 16710 to sit flatter than the "Fat Lady" 16760. Its practical identification tell is visible during setting: the 24-hour hand twitches slightly as the local hour jumps. Cal. 3186 removed that play, so the test distinguishes the two without opening the case.

Cal. 3186

Cal. 3186, engraved "3186"
detail value
type Automatic
jewels 31
frequency 28,800 vph (4 Hz)
power reserve 50h
size 28.5mm × 6.45mm
escapement Swiss lever
balance Monometallic, free-sprung
regulator Microstella screws, no index
shock Shock-absorber, pre-Paraflex

Cal. 3186 ran from 2007 to 2019. It added a Parachrom hairspring to the Cal. 3185 base while retaining 31 jewels, a 28,800 vph frequency, hacking, quickset, and chronometer certification; reserve increased to 50 hours. It powered late 16710 production and the ceramic-bezel 116710LN, 116710BLNR, and 116719BLRO.

The movement has a straight-line lever escapement, monometallic balance adjusted to temperature and five positions, shock protection, a free-sprung Breguet-form hairspring, Microstella regulation, and hacking. One Antiquorum description calls the hairspring blued steel, but Cal. 3186 uses Parachrom, a niobium-zirconium alloy coloured by an oxide layer rather than tempering.

Cal. 3186 retains the Cal. 3135 architecture used by the 3185: 28.5mm diameter, 6.45mm height, 28,800 vph, and 31 jewels. It also keeps the plain-bearing oscillating-weight axle, part 568, shared with Cal. 3130, 3135, 3155, and 3175. Once lubricant migrates, the axle wears and requires replacement and riveting at service.

Rolex introduced Cal. 3186 as a running change, leaving its start date unsettled. Steel 16710 examples begin among late Z- and M-series cases; the lowest documented example is Z 5786xx, but higher Z-series watches can still contain Cal. 3185. Gold references changed earlier. A D-series 116718 catalogued with Cal. 3186 was sold in August 2006, placing the movement in production before the commonly cited 2007 steel transition.

Both Cal. 3185 and 3186 index the local-hour hand with a jumping-hour click. Cal. 3186 reworked the parts and reduced slack between the drive-train wheels. On Cal. 3185, the 24-hour hand twitches when the local hour jumps; on Cal. 3186, it remains still. The test identifies the caliber without opening the case.

The jumping-hour click spring is the caliber's known failure point. A failed spring lets the local-hour hand glide instead of indexing in one-hour steps and can leave it loose on its wheel. Rolex superseded part 657 first with 657-1 and then 657-2; the later springs are stronger and slightly larger. The fault is documented across the 16710, 16570, 116710, 116713, 116718, and 116719, as well as Cal. 3187. It usually leaves other components undamaged. The hour-jump action should be checked on an unserviced watch.

Cal. 3187

Cal. 3187, official Rolex photo, engraved "3187," blue Parachrom hairspring, free-sprung Microstella balance
detail value
type Automatic
jewels 31
frequency 28,800 vph (4 Hz)
power reserve 48–50h (sources disagree)
size 30.97mm (contested; 28.5mm also published)
escapement Swiss lever
balance Monometallic, free-sprung
regulator Microstella screws, no index
shock Paraflex

Cal. 3187 is an enlarged Cal. 3186, widened to move the date window outward in the 42mm Explorer II case. It powered only the 216570 from 2011 to 2021, before Cal. 3285 replaced it in the 226570. The Parachrom hairspring, Breguet overcoil, and independently adjustable local-hour hand carry over from the GMT lineage. Paraflex is new here, replacing the KIF Elastor used by Cal. 3185 and making Cal. 3187 the first movement in this family with Rolex's own shock system.

Cal. 3187 uses a larger baseplate and reworked surrounding parts but retains the Cal. 3186 regulating organ: a straight-line lever escapement, free-sprung monometallic balance under a full bridge, and Microstella regulation without an index. Auction catalogues confirm 31 jewels but do not itemize those inherited components.

Rolex launched the 216570 and Cal. 3187 together in March 2011 for the Explorer II's fortieth anniversary. The 42mm case required the larger movement, while the orange 24-hour hand recalled the 1655. Both remained in production until 2021, and no other reference used the caliber.

Two documented unit commissions use Cal. 3187. A 2012 white-dial 216570 made for members of the British Special Air Service carries "Who Dares Wins," the winged-dagger badge, and its owner's identifiers. A circa-2015 example numbered 40/48 was made for the UK Attack Helicopter Force. These were unit commissions rather than ministry-issued watches and should not be classified with the 5513 MilSub.

Cal. 3187 inherited the 3186's jumping-hour click-spring failure. On affected watches, the local-hour hand glides instead of indexing in one-hour steps. Rolex revised the part twice, and serviced examples may carry the later, stronger spring.

The −2/+2 rating applies only after Rolex redefined Superlative Chronometer in 2015. Earlier watches carried the COSC −4/+6 seconds-per-day standard for the uncased movement; later examples were tested again by Rolex as complete watches. The underlying caliber did not change beyond regulation.

Modern sport calibers (1988–2020)

Cal. 3000 introduced a 28,800-vph no-date movement, followed by Cals. 3130 and 3132. Cal. 3135 powered three decades of Submariner Date production.

Cal. 3000

Cal. 3000
detail value
type Automatic
jewels 27
frequency 28,800 vph (4 Hz)
power reserve 42h (48h in some sources)
size 28.5mm × 5.8mm
balance Adjustable-mass, flat hairspring

Cal. 3000 is the no-date member of the 3000 family, used from about 1990 to 2001 in the Air-King 14000 and 14010, Submariner 14060, and Explorer 14270. The often-quoted 1988 start belongs to Cal. 3135. The Air-King changed to reference 14000M in 2000, while the Explorer became the 114270 and the Submariner adopted Cal. 3130 in 2001. Published power-reserve figures conflict at 42 and 48 hours; no Rolex figure settles the difference.

Cal. 3000 was Rolex's last movement without a Breguet overcoil. It uses a flat hairspring, unlike the outgoing 1570 generation and the rest of the 3000 family. Microstella adjustment sets the rate without an index, the hairspring is glued to the balance stud, and shock protection is KIF. COSC certification used the standard −4/+6 seconds-per-day tolerance.

Cal. 3035

Cal. 3035, engraved "3035," EmmyWatch
detail value
type Automatic
jewels 27
frequency 28,800 vph (4 Hz)
power reserve 48h
balance Free-sprung, four Microstella screws
shock KIF Elastor

Cal. 3035 ran from 1977 to 1988 in the 16800, 168000, 16808, and 16803. It was the first quickset Submariner caliber, with 27 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, and chronometer certification. Compared with the Cal. 1570 generation, it increased frequency from 19,800 vph and added a crown position that advances the date wheel directly. Its free-sprung Nivarox Breguet overcoil is regulated by four Microstella screws and protected by KIF Elastor.

Two construction details separate it from Cal. 3135. Its balance sits on a cantilevered cock, and its hairspring is glued to the stud. Cal. 3135 uses a bridge anchored at both ends and a laser-welded hairspring stud.

Cal. 3130

Cal. 3130, engraved "3130," EmmyWatch
detail value
type Automatic
jewels 31
frequency 28,800 vph (4 Hz)
power reserve 48h
size 28.5mm × 5.85mm
escapement Swiss lever
balance Monometallic Glucydur, free-sprung
regulator Microstella screws, no index
shock KIF Elastor

Cal. 3130 is the time-only successor to Cal. 3000, used in the 14060M, 114060, 114270, and 114200. It brought a full balance bridge, a larger balance wheel, and a Breguet overcoil hairspring. Rolex's parts sheet identifies Cal. 3135 as the base and gives 28.5mm diameter, 5.85mm height, 28,800 vph, and 31 jewels. Published introduction dates range from 1999 to 2001; the precise year remains unsettled.

Cal. 3000 supports its balance from a cock anchored on one side; the 3130 uses a bridge secured at both ends, which stabilizes endshake under lateral shock. Its Glucydur balance is free-sprung, with Microstella nuts setting the rate without an index. KIF Elastor shock protection distinguishes it from the Paraflex-equipped Cal. 3132. At 5.85mm it is 0.15mm thinner than Cal. 3135 because it omits the date mechanism. The main plate is the dedicated part 3130-100, although some smaller components retain 3135 part numbers.

The 14060M initially used Cal. 3130 without COSC certification and carried a two-line dial. Certification arrived in late 2007, adding the two-line "Superlative Chronometer Officially Certified" inscription. The movement itself did not change.

The main wear point is the oscillating-weight axle, Rolex part 568, shared with Cal. 3135, 3155, 3175, and 3185. It runs in a plain sleeve bearing rather than a ball bearing. Once lubricant migrates, axle wear can produce rotor play and fine reddish dust. Replacing and riveting the axle is a routine service repair.

Cal. 3131, announced in 2007, adapts the 3130 for magnetic resistance with a blue Parachrom hairspring, a paramagnetic nickel-phosphorus escapement, and a two-part soft-iron shield around the movement. It powered the Milgauss 116400 and 116400GV, then the Air-King 116900.

Cal. 3132

Cal. 3132
detail value
type Automatic
jewels 31
frequency 28,800 vph (4 Hz)
power reserve 48h
size 30.97mm (contested; 28.5mm also published)
escapement Swiss lever
balance Monometallic Glucydur, free-sprung
regulator Microstella screws, no index
shock Paraflex

Cal. 3132 powered the Explorer 214270 from 2010 to about 2020. It is a Cal. 3130 with a Parachrom hairspring and Paraflex shock protection, retaining 31 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, and chronometer certification.

The base architecture remains a straight-line lever escapement with a free-sprung Glucydur balance under a full bridge, Microstella regulation, and no index. Paraflex replaced the 3130's KIF Elastor settings; Rolex claimed up to 50 per cent greater shock resistance. The blue Parachrom hairspring replaced Nivarox with a paramagnetic niobium-zirconium alloy whose colour comes from a patented oxide treatment.

Cal. 3132 brought Parachrom and Paraflex to the time-only professional line. Parachrom had appeared in Cal. 4130 in 2000, but the Submariner did not receive both features until Cal. 3230 in 2020.

Both dial generations of the 214270 use Cal. 3132. The 2016 revision lengthened the hands and added luminous filling to the 3, 6, and 9 numerals, without changing the movement. Cal. 3132 also retains the 3130's plain-bearing oscillating-weight axle, which wears after its lubricant migrates.

Rolex redefined Superlative Chronometer in 2015, changing the guaranteed rate from COSC's −4/+6 seconds per day on the uncased movement to −2/+2 on the cased watch after additional in-house testing. The movement did not change, so early and late 214270 examples carry different rate guarantees.

Cal. 3135

Cal. 3135, official Rolex photo, engraved "3135," 31 jewels
detail value
type Automatic
jewels 31
frequency 28,800 vph (4 Hz)
power reserve 48h
size 28.5mm
escapement Swiss lever
balance Free-sprung Glucydur, four Microstella nuts
regulator Free-sprung, no index
shock KIF (never Paraflex)

Cal. 3135 ran from 1988 to 2021 with 31 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, quickset, and chronometer certification. It powered the 16610, 16613, and 16618 through the 116610 generation. The Submariner changed to Cal. 3235 with the 126610 on 1 September 2020, but the Oyster Perpetual Date 34 references 115200 and 115234 kept Cal. 3135 in production into 2021. Later end dates conflate it with Cal. 3131. The movement has rhodium plating, bevelled and polished screws, and a two-piece axle-style bidirectional rotor.

The conventional Swiss lever escapement is paired with a free-sprung Glucydur balance. With no index or curb pins, four Microstella nuts on the inside of the rim set the rate by changing the wheel's inertia. Older 1530-family balances place their adjustment screws on the outside. Cal. 3135 uses a Breguet overcoil and laser-welds the hairspring to its stud, replacing the glued joint used by Cal. 3035.

The main architectural change from Cal. 3035 is the balance bridge. Part 3135-120 is secured at both ends and carries height-adjusting nuts, keeping the pivots aligned under load and allowing endshake adjustment without shims. It also prevents the hairspring from fouling a cantilevered balance cock, a known Cal. 3035 problem. Cal. 3135 increased the jewel count from 27 to 31 and uses a larger balance wheel.

Cal. 3135 used KIF shock protection throughout its run and never received Paraflex. Rolex assigned new caliber numbers to Paraflex versions: 3130 became 3132, 3155 became 3156, and 3186 became 3187. The larger Paraflex date movement for the Datejust II was Cal. 3136. A 16610 or 116610 described as having Paraflex is misidentified.

Parachrom arrived during the Cal. 3135 run, but the transition date is unsettled. The niobium-zirconium alloy receives a uniform anodised oxide layer about 50 nanometres thick, which gives the hairspring its blue colour and stabilizes its restoring torque. Published dates for its adoption in Cal. 3135 range from about 2005 to 2009, with transitional examples reported on both sides. The ceramic-bezel 116610 uses it consistently from 2010. The spring's colour provides only a rough dating marker.

Two wear points sit in the automatic works. The anodised purple-red reversing wheels, part 3135-540, are visible through the rotor cutout and identify the movement without disassembly. Failure produces free rotor spin without winding or gritty manual winding. Epilame belongs across the reverser assembly, while oil is confined to the arbor and bearing points; oil on the teeth or clicks can jam the mechanism. The oscillating-weight axle, part 3135-568, runs in a plain jewelled sleeve. Wear causes a rattle, rotor contact with the caseback, and red dust in the movement. Rolex supplied mainsprings in standard part 3135-311 and weaker 3135-311-1 versions, a relevant distinction when assessing a rebuilt movement.

A freshly serviced Cal. 3135 should show about 270 to 310 degrees of amplitude when fully wound. More than 335 degrees can indicate that the mainspring bridle is slipping too late because it lacks braking grease; Rolex sets a minimum of 200 degrees after 24 hours in the worst position. Earlier movements carried COSC's −4/+6 seconds-per-day standard. From 2015, Rolex applied its −2/+2 Superlative Chronometer test to the complete watch without changing the caliber. Derivatives include Cal. 3155, 3175, 3185, 3186, 3187, and the no-date 3130, 3131, and 3132.

Milgauss

Rolex introduced the documented Milgauss calibers about fifty years apart. Rolex adapted its contemporary sport movements for the Milgauss: Cal. 1580 derives from the 1530 platform, and Cal. 3131 from Cal. 3130.

Cal. 1580

Cal. 1580, marked "26 Jewels, Adjusted Six 6 Positions" — EmmyWatch
detail value
type Automatic
jewels 26
frequency 19,800 vph (2.8 Hz)
power reserve 48h
size 28.5mm × 5.75mm
escapement Straight-line lever
balance Free-sprung monometallic, Microstella screws
regulator None — free-sprung
shock Shock absorber

Cal. 1580 is associated exclusively with the Milgauss 1019 during its 1960–1988 run, subject to the early-production dating conflict below. It shares the 1530-derived platform with Cal. 1570 and 1575, and gained hacking around 1972. A soft-iron inner shield around the movement provides the magnetic protection, making the 1019 thicker than contemporary Submariner and GMT-Master cases using the same movement family. Parts interchange broadly across the 1520/1525/1530/1535/1555/1556/1560/1565/1570/1575/1580 group.

Cal. 1580 has 26 jewels, a straight-line lever escapement, a monometallic balance adjusted to temperature and five positions, shock protection, and a Breguet hairspring. Antiquorum describes the hairspring as free-sprung white metal with Microstella regulation. That matches Cal. 1560 and 1570 on the same platform, although no second auction house specifies the regulation system.

The case provides the magnetic shielding. A gilt-metal anti-magnetic cap and the surrounding inner case absorb the field. Cal. 1580 uses the standard 1530-family balance and hairspring inside the shielded case. Rolex added hacking in 1972 with the corresponding sport-caliber revision.

The factory caliber table introduces Cal. 1580 in 1963, three years after the 1019's generally accepted launch around 1960. It lists the earlier anti-magnetic Cal. 1065M, 1066M, and 1080 from 1955, and a Milgauss 6541 is documented with Cal. 1080. Published evidence does not settle whether the earliest 1019s used Cal. 1580 or one of these 1030-family movements.

Cal. 3131

Cal. 3131 from a Milgauss 116400GV, auto bridge and gold reversing wheels
detail value
type Automatic
jewels 31
frequency 28,800 vph (4 Hz)
power reserve 48h
size 28.5mm
escapement Nickel-phosphorus escape wheel & pallet fork
balance Free-sprung monometallic, Microstella
shock KIF

Cal. 3131 is a no-date Cal. 3130 derivative announced at Baselworld 2007 for the Milgauss 116400 and 116400GV "Glace Verte." From 2016 it also powered the Air-King 40 reference 116900. Magnetic protection has three parts. A two-piece ferromagnetic shield encloses the movement, with one half secured on the dial side and the other beneath the outer caseback; the inner back carries a capital "B" and arrow, the symbol for magnetic flux density. The movement also uses a paramagnetic blue Parachrom hairspring and an amorphous nickel-phosphorus escape wheel and pallet fork.

Cal. 3131 remained COSC-certified throughout its run, with KIF shock protection and a conventional Swiss lever escapement. It never received Chronergy or Paraflex. Rolex applied the tighter −2/+2 seconds-per-day Superlative Chronometer standard from 2015, so later 116900 and 116400GV examples carry the revised rating without a corresponding movement change. The Air-King remained in production to 2022 and the Milgauss to 2023.

Daytona chronograph (manual-wind)

The manual-wind Daytona used Valjoux 72 architecture from 1963 through 1988. Across five caliber numbers, Rolex progressively refinished and re-rated the Valjoux 72 ébauche.

Valjoux joined the Ebauches SA group in 1944 and was later folded into ETA, though the Valjoux name remained in use through the end of Cal. 72 production in 1974. At least 62,000 Valjoux 72/23 movements are recorded in Rolex cases across more than 40 references, about 7 per cent of total output. Heuer, Universal Genève and Longines also used the base. Rolex examples differ in their finishing and adjustment.

Cal. 72

Valjoux 72 ébauche, caliber "72" stamped at 6 o'clock beside the Valjoux logo, plate marked "Seventeen 17 Jewels Unadjusted," stock index regulator with F/A–S/R scale — the untouched configuration Rolex fitted as Cal. 72. This example's chronograph bridge is signed Heuer-Leonidas SA
detail value
type Manual
jewels 17
frequency 18,000 vph (2.5 Hz)
power reserve 48h
escapement Swiss lever
shock Incabloc

Used in the pre-Daytona ref. 6234 from about 1955 to 1961, Cal. 72 remained close to the Valjoux ébauche. Rolex retained its index regulator, flat hairspring and Incabloc protection. Auction records document the bare Cal. 72 designation on examples from 1957 and around 1960; published production dates for the 6234 end in either 1960 or about 1961.

Cal. 72A

detail value
type Manual
jewels 17
frequency 18,000 vph (2.5 Hz)
power reserve 48h
escapement Swiss lever
shock Incabloc

Cal. 72A appears in late ref. 6234s from the late 1950s to about 1961. It retains the index regulator and flat hairspring that Cal. 72B would replace, making it a Rolex-finished but otherwise conventional Valjoux 72 execution. The meaning of the ROW stamp remains uncertain: Sotheby's associates it with US importation, while Grail Watch Reference reads it as Rolex Werke. Neither interpretation is supported by a known Rolex document.

Cal. 72B

Rolex-signed Valjoux 72-family movement, seventeen jewels — caliber sub-variant not distinguishable from the engraving alone
detail value
type Manual
jewels 17
frequency 18,000 vph (2.5 Hz)
power reserve 48h
escapement Swiss lever
balance Microstella, adjustable inertia
shock KIF (often Flector)

Used in the ref. 6238 and the last 6234s, Cal. 72B marks Rolex's first substantial reworking of the Valjoux base. The index regulator gave way to a Microstella adjustable-inertia balance, the flat hairspring to a Breguet overcoil, and Incabloc protection to KIF, often in its clover-shaped Flector form. The caliber also has the earlier screwed setting lever, later replaced by a pusher type.

The transition date is disputed. Dody Giussani's text for Ultimate Rolex Daytona dates the complete replacement of Cal. 72A to 1966, while auction records identify Cal. 72B in ref. 6234 examples from around 1961. Giussani finds no substantial mechanical difference between the 72B and 722 and notes that Rolex used both names in its technical documents. The regulating organ changed before Rolex consistently adopted the later caliber name.

Cal. 722

Rolex-signed Valjoux 72-family movement, seventeen jewels — caliber sub-variant not distinguishable from the engraving alone
detail value
type Manual
jewels 17
frequency 18,000 vph (2.5 Hz)
power reserve 48h
escapement Swiss lever
balance Microstella, adjustable inertia
shock KIF (often Flector)

Cal. 722 powered the refs. 6239, 6240 and 6241, including examples with "Paul Newman" dials. Its column wheel controls a horizontal clutch through a coupling yoke. Engagement can make the chronograph hand jump slightly forward or back at the start, a trait later removed by the vertical clutch in Cal. 4130.

The position of the "Rolex Genève" inscription on the dial-side plate distinguishes Cal. 722 from the 722-1 that followed. The designations otherwise overlap: Christie's records Cal. 72B, 722 and 722-1 across ref. 6241 production. The engraving on the movement is more reliable than a date-based attribution.

Cal. 722-1

Rolex-signed Valjoux 72-family movement, seventeen jewels — caliber sub-variant not distinguishable from the engraving alone
detail value
type Manual
jewels 17
frequency 18,000 vph (2.5 Hz)
power reserve 48h
balance Microstella (inherited from 722)
shock KIF

Introduced in 1967, Cal. 722-1 was the last 18,000 vph Daytona caliber before Cal. 727 raised the frequency. Rolex described it as a Valjoux 72A-based mechanism with the same dimensions as its predecessor; the changes were internal.

The hour-recorder conveyor gained an eccentric pivot and wing-shaped spring, allowing more precise engagement with the hour wheel. A guard spring above the balance was intended to keep the hairspring on its stud support under shock. Giussani records that the guard had already appeared inconsistently on Cal. 722 and caused problems of its own, so many surviving examples of both calibers lack it.

Cal. 727

Cal. 727 (right, engraved 727, Daytona ref 6265), specialist comparison photo via Perezcope
detail value
type Manual
jewels 17
frequency 21,600 vph (3 Hz)
power reserve 48h
escapement Swiss lever
balance Microstella, adjustable inertia
shock KIF

Cal. 727 raised the Valjoux 72 frequency from 18,000 to 21,600 vph and powered the refs. 6262, 6263, 6264 and 6265 from 1970 until 1988. A genuine example has a Breguet overcoil and a bevelled inner edge on the KIF shock-spring retaining ring. These details, together with the engraved caliber number, help distinguish an original movement from a substituted or counterfeit one.

Daytona chronograph (automatic)

Cal. 4030

Cal. 4030, engraved 4030, thirty-one jewels
detail value
type Automatic
jewels 31
frequency 28,800 vph (4 Hz)
power reserve 52–54h (sources disagree)
balance Free-sprung Breguet
escapement Swiss lever

Launched with the ref. 16520 in 1988, Cal. 4030 was a heavily reworked Zenith El Primero 400 and the last externally designed movement used by Rolex. Rolex removed the date, reduced the frequency from 36,000 to 28,800 vph and changed more than half of the components. A Breguet overcoil replaced the flat hairspring, while a free-sprung Glucydur balance with Microstella regulation and KIF protection replaced the Zenith oscillator. The chronograph retained a column wheel and horizontal clutch.

Published power-reserve figures split between 52 and 54 hours, with no known Rolex document settling the difference. The photographed movement is signed "MONTRES ROLEX S.A. GENEVA SWISS, ADJ. 5 POSITIONS TEMPERATURE, THIRTY-ONE JEWELS" and stamped "4030."

Cal. 4130

Cal. 4130 movement detail, bridge marked "4130"
detail value
type Automatic
jewels 44
frequency 28,800 vph (4 Hz)
power reserve 72h
escapement Swiss lever, 52° lift angle
balance Free-sprung, four gold Microstella nuts
shock KIF

Cal. 4130 was Rolex's first chronograph movement of its own design, launched with the ref. 116520 in 2000. Its column wheel and vertical clutch provide clean chronograph engagement without the hand jump associated with Cal. 4030. The movement uses 201 components, about 20 per cent fewer than its predecessor, and twelve types of screw rather than more than forty.

The rotor runs on a ball bearing; the Cal. 3135 generation uses a jewelled sleeve. Claims that the bearing is ceramic lack support from Rolex or specialist documentation. The free-sprung balance sits under a transversal bridge and uses KIF protection. Chronergy, Paraflex, an optimised rotor bearing and Côtes de Genève arrived with Cal. 4131 in 2023. The display back also belongs to that successor and was limited to platinum; every Cal. 4130 Daytona has a solid caseback.

Parachrom was fitted from launch, but the blue version is variously dated between about 2005 and 2007 without a supporting Rolex document. Later examples were rated to Rolex's −2/+2 seconds-per-day standard after its introduction in 2015. Cal. 4130 continued through the ref. 116500LN until Cal. 4131 replaced it in March 2023.

Day-Date

Day-Date calibers form their own family. Four-digit references set both calendar displays through the hands; five-digit references introduced quickset.

Cal. 1055

Cal. 1055, period parts-catalogue illustration, front and back
detail value
type Automatic
jewels 25
frequency 18,000 vph (2.5 Hz)
power reserve 42h
escapement Straight-line lever
balance Monometallic
shock KIF

Cal. 1055 was Rolex's first day-and-date movement, used from 1956 to 1959 in the refs. 6510, 6511, 6611, 6612 and 6613. Its rhodium-plated bridges carry oeil-de-perdrix ("partridge-eye") circular graining rather than Côtes de Genève. Documented examples were adjusted to temperature and five positions.

The ref. 6611 replaced the 6511 in 1957 with an improved chronometer-certified version engraved 1055B on the bridge. Its dial reads "Superlative Chronometer Officially Certified" rather than the earlier "Officially Certified Chronometer."

The arrival of the free-sprung Microstella balance is disputed. The usual account places it with the 66xx revision, but an auction description identifies a first-generation 6511 as free-sprung. Neither generation has quickset or hacking.

Cal. 1555

Cal. 1555, rotor bridge detail
detail value
type Automatic
jewels 25
frequency 18,000 vph (2.5 Hz)
power reserve 42h
size 7.03mm
escapement Swiss lever (Cal. 1530 train)
balance Free-sprung beryllium-bronze, Microstella screws
shock KIF Flector

Cal. 1555 powered early four-digit Day-Dates, including the refs. 1803, 1804, 1806, 1807 and 1811, from 1959 to about 1967. It combines the day-and-date architecture of Cal. 1055 with the plate and most running components of Cal. 1530. Its distinct parts are concentrated in the motion and calendar work, some shared with the contemporary Datejust Cal. 1575.

The Swiss lever escapement comes from Cal. 1530 and uses KIF Flector protection. The free-sprung balance uses a Nivarox Breguet overcoil and screw-shaped Microstella adjusters. Rolex did not adopt the later nut-shaped Microstella components until 1983.

Cal. 1555 does not hack; unlike the 1972 revision of Cal. 1556, its parts list has no balance-stop spring. Wear in the mainspring-barrel bearing is a known fault. As the plate and bridge bores wear out of round, the barrel can tilt and reduce amplitude; Rolex supplied a replacement upper barrel bush for the repair.

Five stainless-steel Day-Dates are publicly known, none with a listed reference or case serial. Christie's records movement numbers 0004547, 0005073, DD411420, DD14749 and DD081221. Their casebacks are signed Rolex and stamped "Stainless Steel"; the known examples have French day discs, black hands and silvered dials, with provenance linked to former Rolex watchmakers. Christie's identifies them as workshop test pieces. Movement DD411420 is engraved 1555 but runs at the Cal. 1556 frequency of 19,800 vph, placing it between the two generations.

The prototype's jewel count is disputed. Antiquorum gives 25, matching the bridge signature, while Phillips gives 26, the figure for Cal. 1556. At 7.03mm, Cal. 1555 is the thickest member of the 1500 series. The stepped "pie-pan" dial remained in use until about 1970, outlasting the caliber.

Cal. 1556

Cal. 1556
detail value
type Automatic
jewels 26
frequency 19,800 vph (2.8 Hz)
power reserve 42h
escapement Swiss lever, 52° lift angle
shock KIF Flector, both balance pivots

Cal. 1556 succeeded the 1555 around 1965 and powered the mid- and late four-digit Day-Date until 1977 or 1978. A revised gear train raised the frequency, while a jewel at the top of the centre wheel brought the count to 26. Its rhodium-plated movement has perlage finishing, a full balance bridge and a screwed balance with two gold, star-shaped Microstella regulating screws. Hacking was added during production in 1972 without a new caliber designation; earlier examples do not hack.

Cal. 1566

detail value
type Automatic
jewels 26
escapement Straight-line lever
balance Monometallic, free-sprung Breguet spring

Cal. 1566 was built for one case, the platinum Day-Date 1831 commissioned for the Shah of Iran and delivered from 1977. At 290 grams, it is the heaviest production Rolex. The rhodium-plated movement has a free-sprung Breguet hairspring, Microstella regulation and hacking. Sources record either eight or nine examples. One concordance assigns the ref. 1831 to Cal. 1556, while auction houses that examined the watches identify Cal. 1566.

Cal. 3055

Cal. 3055, period parts-catalogue illustration with day-disc
detail value
type Automatic
jewels 27
frequency 28,800 vph (4 Hz)
power reserve 48h
escapement Swiss lever
balance Free-sprung Glucydur, Microstella
shock KIF

Cal. 3055 powered the refs. 18038, 18048, 18078 and early 18238 from 1977 to 1988. It introduced quickset for the date, while the day still advanced through the motion of the hands. The balance cock provides the clearest visual distinction from Cal. 3155, which uses a full transversal bridge. Common references give a height of 6.3mm, but Rolex's parts diagram specifies 7.11mm.

Cal. 3155

Cal. 3155, engraved "3155," EmmyWatch
detail value
type Automatic
jewels 31
frequency 28,800 vph (4 Hz)
power reserve 48h
balance Free-sprung Glucydur, Microstella
shock KIF Elastor

Cal. 3155 replaced the 3055 in 1988 and remained in production through 2019. It added independent correction of the day, giving the Day-Date a double quickset for both calendar displays.

The added quickset works raised the jewel count from 27 to 31. Published height figures vary between 6.00 and 6.45mm, with no known Rolex document settling the discrepancy. As elsewhere in the 31xx family, a full bridge and larger balance wheel replaced the older balance cock.

The hairspring stud is laser-welded rather than glued as on Cals. 3035 and 3055. Parachrom arrived between 2008 and 2010 according to Grail Watch Reference, or by 2013 according to Watch Wiki. Cal. 3155 retained KIF Elastor throughout and never received Paraflex, which Rolex fitted to the Day-Date II's Cal. 3156.

Cal. 3156

Cal. 3156, engraved "3156," Day-Date II official brochure image
detail value
type Automatic
jewels 31
frequency 28,800 vph (4 Hz)
power reserve 48h
size 30.97mm
escapement Swiss lever, 31xx family (pre-Chronergy)
balance Parachrom hairspring (3155 base)
regulator Free-sprung, gold Microstella nuts, traversing bridge
shock Paraflex

Cal. 3156 is a widened Cal. 3155 derivative built for the 41mm Day-Date II from 2008 to 2015. It adds a Parachrom hairspring and Paraflex protection and powers the refs. 218238, 218239, 218206 and 218235. Its 30.97mm main plate carries the enlarged calendar wheels needed to move the date window outward. The same wider format appears on Cals. 3132, 3136 and 3187. Published specifications often give the standard 28.5mm width, but Rolex's promotional photography shows the additional flange recorded by Stephen Foskett's Grail Watch Reference.

Only the plate-and-bridge layer is oversized. The running train, escapement, keyless works and date mechanism use standard 31xx-family components, while structural parts such as the barrel bridge are shared with the wider Cals. 3132, 3136 and 3187 rather than the 3155.

The oscillator comes from Cal. 3155: a large free-sprung balance with gold Microstella nuts, a Breguet overcoil and a height-adjustable transversal bridge. Below it is the conventional Swiss lever escapement used across the 31xx family. Its 2015 successor, Cal. 3255, introduced the paramagnetic nickel-phosphorus Chronergy escapement. Rolex credits that design with a 15 per cent efficiency gain and about half of the increase from 48 to 70 hours of power reserve.

Cal. 3156 uses Paraflex shock protection; Cal. 3155 retains KIF Elastor. Rolex filed the design in 2005, and the European patent was granted in 2008. Its spring connects to the bearing body through four arms arranged around a central support, replacing the two-arm layout common to earlier systems. Rolex claims up to 50 per cent greater shock absorption than KIF, but no independent test is cited.

Cal. 3156 was confined to the 41mm Day-Date II. Rolex retired both in 2015, replacing them with the 40mm Day-Date and Cal. 3255, while the 36mm Cal. 3155 remained in production until 2019. Most Cal. 3156 watches carried the COSC −4/+6 seconds-per-day standard. Rolex adopted its −2/+2 rating in the caliber's final year, 2015.

Oysterquartz

Rolex produced fewer than about 25,000 Oysterquartz watches between 1977 and 2001. The line followed the Beta 21-powered ref. 5100 of 1970, developed through the Centre Electronique Horloger consortium. The Beta 21 would not fit an Oyster case, and the ref. 5100 was water-resistant rather than waterproof. Rolex left the consortium in 1972 and spent five years developing Cals. 5035 and 5055 in-house.

Cal. 5035

Cal. 5035, engraved "5035," "11 ELEVEN JEWELS," "1.55V," EmmyWatch
detail value
type Quartz
jewels 11
frequency 32,768 Hz crystal
drive Mobile-frame step-by-step motor, pallet fork, 1 beat/s
circuit C-MOS module: oscillator, binary divider, impulse amplifier
rate adjustment Trimmer, about 2 s/d total range
battery 1.55V silver-oxide, 24+ months
size 29.75mm diameter (29.00mm case-fitting), 6.35mm high

Cal. 5035 powered Oysterquartz Datejust and Oyster Perpetual references, including the 17000, 17013 and 17014, from 1977 to 2001. Its date mechanism follows the same principle as the mechanical Cal. 3035 introduced in the same year.

Rolex calls the drive a mobile-frame step-by-step motor. Unlike a conventional quartz stepper, its coil moves while the magnets remain fixed. A polarised pulse swings the coil frame once per second, and a finger on the frame drives a pallet fork connected directly to the seconds wheel. The pallet locks the wheel between pulses. Its audible tick comes from that engagement and sounds closer to a mechanical escapement than a conventional quartz motor.

The C-MOS module contains the oscillator, a binary divider that reduces 32,768 Hz to one pulse per second, and the motor's impulse amplifier. A trimmer provides a total adjustment range of about two seconds per day. Rolex specified regulation to ±0.05 seconds per day at about 28°C.

Temperature compensation remains uncertain. Secondary accounts describe a thermocompensated oscillator with a thermistor, but Rolex's technical document mentions neither. It instead shows a parabolic rate curve with an inversion point at 26 ±2°C and specifies adjustment near the 28°C temperature of a worn watch. The document may predate a later revision, but it does not support the usual thermistor claim.

Rolex specified accuracy within one minute per year under normal wear and battery life beyond 24 months. The movement draws no more than 9 microamps, of which the electronics use at most 3. There is no battery end-of-life indication; erratic running is the warning. Hacking cuts current to the motor, and the seconds hand restarts one second after the crown returns to its running position.

The electronic module and motor are sensitive to contamination, and the mobile-frame pivots run dry. Rolex supplied the motor only as a complete unit rather than as separate components.

Cal. 5055

Cal. 5055, engraved "5055," "11 ELEVEN JEWELS," EmmyWatch
detail value
type Quartz
jewels 11
frequency 32,768 Hz crystal
drive Mobile-frame step-by-step motor, pallet fork, 1 beat/s
circuit C-MOS module: oscillator, binary divider, impulse amplifier
rate adjustment Trimmer, about 2 s/d total range
battery 1.55V silver-oxide, 24+ months
size 29.75mm diameter (29.00mm case-fitting), 7.11mm high

Cal. 5055 is the Day-Date counterpart to Cal. 5035. The two share their motor and electronic module, while the 5055's calendar follows the principle of the mechanical Cal. 3055. Its day-disc stack increases the height from 6.35 to 7.11mm.

Cal. 5055 was COSC-certified from its 1977 launch. Cal. 5035 gained certification around 1978–80, alongside a change to a tuning-fork-shaped quartz crystal, so early Oysterquartz Datejust dials lack the "Superlative Chronometer Officially Certified" text found on contemporary Day-Dates.

Cal. 5055 adds the day mechanism and its stricter tolerances. Rolex specified hour-wheel endshake below 0.03mm and calendar change within two minutes of midnight. The day disc is a separate replaceable part, allowing the display language to be changed without altering the movement.

Cal. 5055 powers the yellow-gold ref. 19018, white-gold ref. 19019 and pyramid-bezel ref. 19028. Planned successors, Cals. 5235/5255 with a conventional stepper motor and 5335/5355 with a perpetual calendar, were cancelled before production.

Related but not Rolex

Gruen Cal. 877 and the Bubbleback-era "9¾ ligne" description are often misidentified as Rolex calibers. Gruen's Cal. 877, used in the Techni-Quadron, is an Aegler-built architectural sibling of Cal. 300 sold under Gruen's name in the United States. It was never a Rolex commercial number. A Bubbleback-era "9¾ ligne" description records only the movement's size class, not a distinct caliber designation.

Sources

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