How to Identify a Vintage Omega [2019]

 In Collecting Watches

Omega is a great brand. Both the new and the vintage models are fantastic.

However, if you buy a new one from an AD or boutique, the risk of buying a lemon is very low. You can buy one with a factory flaw, but that’s out of your hands. With vintage Omegas, it’s anything but easy. Nevertheless, I’d like to provide some guidelines.

In this article, I’ll show you exactly how to identify a vintage Omega watch.

This article was originally published on April 20, 2019. It was updated and newly published on November 14, 2019.

Identifying the movement

Please don’t buy a vintage watch, let alone an Omega, without having a look at the movement. If you ask the seller for pictures of the movement, and you get a response like “I can’t” or “I don’t have the tools” or just a plain “no,” it’s best to skip that one.

Omega movements, from the 1930s and 1940s, usually have the calibre number under the balance. From the late 1940s on, the number was located on one of the bridges, often the same one as the serial number.

Serial numbers

Every Omega movement has a serial number. In pocket watches from the early 1900s, you can find it on the dial side of the baseplate. In other words, you have to disassemble the watch to access it. Later on, the serial was always on one of the bridges.

You can find a list of serial numbers for Omega at Chronomaddox, a useful Omega resource created by the late Chuck Maddox. Note that this list doesn’t apply to Speedmasters. Speedies have a separate list, compiled by Roman Hartmann, and you can check it here.

30mm movements

The 30T2 and its derivatives are a legend in their own right. They can be tricky, though.

30T2 and derivatives

Note that various versions of the calibre 30T2 sometimes have a signature of the base calibre, while that’s not necessarily the full calibre number. For example, the 30T2 PC and 30T2 PC AM are both signed 30T2 PC, because the only difference is an anti-magnetic balance in the AM version.

How to identify a vintage Omega

Calibre 30T2 PC AM from a ref. MI 2214/9. The serial number dates it to 1946 or thereabouts. Note the absence of “AM” in the markings under the balance.

The Ranfft movement archive entries for movements of various Omega families list differences between particular movements of a calibre family. It’s always good to check that out when looking at a movement.

For example, when you see a cal. 265 with a flat hairspring, while it’s supposed to have a Breguet overcoil, you can be sure that it’s a 269 movement with the wrong balance.


The 30T2 had a few chronometer versions, all of a higher grade than the non-chronometer versions. These have the suffix RG in the number. You can easily recognize the RG by its distinctive regulator.

I’ve encountered cases where a dial signed “Chronometre Omega” was fitted to a non-RG 30mm movement. This is – and will always be – wrong. A non-RG 30mm movement + a “chronometre” dial = frankenwatch. No exceptions.

60X series

This is nothing more than a 5XX base without the automatic winding assembly. Of course, the barrel is different as well. They were mostly used in the Geneve collection. However, a few Seamaster De Ville models had it as well.

Theoretically, it fits in a case intended for a 5XX. If you see a 60X series movement in a case with a reference that tells you it’s a model which is supposed to be equipped with a 5XX-series automatic, that’s wrong.


Until the 1990s, the only supplier of chronograph movements for Omega was Lemania. One of the best-known ones is the cal. CH27 C12, later known as the cal. 321. There are, however, differences between the CH27 C12 and the 321.

The 321 is always marked as such and always has copper-colored plating. So, if you’re checking out an Omega chronograph from the 1950s, which is supposed to have a cal. 321, but it has a silver-colored finish on the plates, cocks, and bridges, and it doesn’t have the 321 markings, it’s simply not a 321.

Rotor automatics and their issues

Omega’s rotor automatics of the 5XX family (and everything that followed) are great. Still, they have a few problems worth noting.

You need to be extremely careful with signs of issues with the rotor. The one thing that’s known to go wrong with these movements is the axle of the rotor. When it wears out, the rotor will start rubbing against the bridge on which it sits (upper bridge for automatic device), and against the case back. The edge on the rotor will have a noticeable loss of plating. So will the upper bridge, most likely. The inner side of the case back will have a characteristic circular trace on it.

When you see that, best skip that one. It may be that the issue has been repaired. But can you be sure? Nope.

It’s also not uncommon to see movements built from spare parts. You can often spot them by an inconsistent tone of the plating throughout the various components. Of course, some parts will change color due to the different solutions they were cleaned in during a service. However, if one part has an almost yellow gold color, and the other one has a deep, dark copper tone, you can be sure they didn’t leave the factory together.

Another example of frankenising is using parts from Tissot counterparts in movements, which the two brands shared. Notably, that’s the case with the Omega 1480 and the Tissot 2471. Well, technically they’re the same thing. So, the parts are interchangeable.

I’ve seen rotors from the Tissot transplanted in an Omega. If you see something like that, skip that one.

Location of the markings

The general rule is that Omegas have all the relevant markings on the inner side of the case back. These should include a reference or serial number, the Omega stamp in a triangular frame, and the case material. Sometimes, and that usually applies to the 1950s and 1960s pieces, you can also find some info about the manufacturer of the case.

Case back Omega Speedmaster 145.022

This is the case back of an Omega Speedmaster 145.022 from 1984. The CRS at the bottom means that Spillmann made the case.

Some pieces don’t follow this pattern. For example, the two collections made for the Swedish market – the Suveran, and the Officer. These had the markings on the outside of the case back.

Also, many US market models were cased locally, in cases made by American suppliers. These often had the case material marked on the outside.

Case serial numbers

While Omega’s reference numbers start somewhere in the 1930s, they were usually not placed on the watch itself until the mid-1940s. Notable exceptions include the Naiad and Medicus models, which did sometimes have the reference stamped on the case back.

The case serials follow the same code as the serial numbers found on movements. There shouldn’t be much of a gap between the case and movement serial – 2 years tops. Note that if it’s three, for example, that doesn’t disqualify the watch. Omega has a record of pairing movements and cases from batches made within a considerable period.

While the reference numbers started to appear on cases regularly in the mid-1940s, the latest serial-stamped cases I’ve seen dated to 1947-1948. This especially applies to chronometers equipped with the 30T2 RG (all variants of the RG).

Case material codes

A two-letter case material code preceded every Omega reference. This was rarely found on the case.

It was also – at times – not very consistent. For example, with 3-, 4- and 5-digit reference numbers, the standard code for stainless steel was CK. Still, there were models in stainless steel, where the code was MI.

For watches made until the early 1960s, the codes were as follows:

  • Steel: CK/MI
  • Solid gold: OT/OJ
  • Gold cap: KO
  • Gold-filled: PK

Remember that if a reference was made in a few case material versions, the base reference number will always be the same.

So, let’s assume that you’re checking a 4-digit reference in the Omega Vintage Database (OVD) on the Omega website. The only result is a watch in solid gold, while the one you’re looking at is stainless steel. This doesn’t mean that there’s anything wrong with the watch. It’s just that you’re looking at a CK, the steel version, and the watch that is listed in the OVD is an OT/OJ, in other words, a version in solid gold.

The OVD misses plenty of entries, both entire models and different versions of listed watches.

3-, 4-, and 5-digit reference numbers

It’s unknown if these reference numbers have any meaning. I don’t suppose they’re completely random, but there aren’t any means of decoding them.

The four-digit references were used until the early 1960s.

In the late 1950s, Omega introduced a short-lived 5-digit system, paired with the same material codes as the 4-digit system. It was mostly phased out by 1962/1963.

The 6-digit system

In 1962, Omega introduced a new system of case reference numbers. By the 1970s, it was changed again, to a 7-digit system.

Case back Omega Seamaster De Ville

The case back/unishell case of an Omega Seamaster De Ville with the reference number 136.020. The CB at the bottom means that Centrale Boites made the case.

Still, the principle remains the same for both systems, that the first three digits define the characteristics of a watch. A key for this can be found here, along with case material codes for 6- and 7-digit reference numbers. So, if you look at the ordinary Speedmaster reference, 145.022, 145 means: (1)Gent’s watch (4) Manual winding chronograph (5) Water-resistant.

Keep in mind, that the OVD might require you to add a 0 after the period in a 6-digit reference to look it up. For example, a 145.022 becomes 145.0022 in the search.

American market references

While models with ordinary reference numbers were available in the US, Omega has made some watches for the US market only. Only a few of these are listed in the OVD.

Usually, the references of these models had the prefix “G.” If you come across one of these, chances of finding it in the OVD are slim. Again, this means that a watch isn’t listed there, which sadly isn’t uncommon.

Two references on one case?

That’s not unheard of. Some cases were used for two different models. The difference between them could be a completely different dial and handset. Sometimes, though, it was the movement.

Omega DeVille Quartz case back

The case back from an Omega DeVille Quartz with two reference numbers.

Now and then, one reference could have been used with two or three different movements. Apart from one reference spanning over two or three generations of a used movement, this is also the case with pieces made for the US market. The movement in these had a different number due to a different (lower) jewel count. They had fewer jewels to avoid a higher import tariff in the US.

A collection-specific number on an unsigned watch

What if the watch you’re looking at has a reference number that tells you it’s a Seamaster, but it doesn’t say Seamaster on the dial? That’s quite common. One reference could have belonged to two collections at the same time (for example, Seamaster and Geneve), and yet the watch was also available with no collection name on the dial.

A noteworthy example of a shared reference is the Seamaster 600, which was also available as a Geneve. But there, the Seamaster always had the hippocampus logo on the back. A plain back + Seamaster 600 dial = a “franken” or a redial.

Keep in mind that a reference that was shared between different collections was a thing of the 1960s and 1970s. In the 1950s, a Seamaster reference on a watch with an unmarked dial only means that the watch was available without the collection name. Also, for a Seamaster made before ca.1958, the absence of the hippocampus logo is OK. That logo appeared on SM cases only from very late in 1957.

It’s the year of introduction that matters. For a reference introduced before 1957, the absence of the logo on a specimen from 1958 or 1959 is nothing strange.

Locally made cases

This only applies to watches that were made for the US and UK markets. Steel cases were always made in Switzerland, along with the rest of the watch. However, gold-plated and gold-filled ones for the US market were made by local suppliers, like Wadsworth.

In the UK, solid gold cases, especially the ones with the typical British purity of 9ct, were made locally by Dennison (ALD). A Dennison Omega case always has the following markings:

  • Omega stamp
  • Reference or serial number
  • Purity mark
  • Assay office stamp (London, Birmingham, Glasgow, etc.)
  • A “date letter” corresponding to the year of manufacture of the case. Every assay office had a different letter assigned to a specific year.

The calibre doesn’t match the case

The first and most obvious reason for that is that the watch is a “franken,” which means that it has been assembled from random parts
However, there’s one exception.

Always check if the movement in the watch isn’t a US version of the movement mentioned in the OVD. These will have a US import code (OXG) on the balance cock, and a lower jewel count. The OVD often doesn’t list the US version of a particular reference.

This is true for almost all families of Omega rotor automatics: 4XX, 50X, 55X, 56X, 59X, 71X, and 1XXX series. For example, the jewel count is the only difference between the 470 and 471, 490 and 491, 550, and 552. And so on.

You can find the details of the differences in the Ranfft archive. Every entry for movements within a particular family list the differences between the movements within that family.

Otherwise, as mentioned in the previous part of the series, a movement that doesn’t match the case is a red flag.


Keep in mind that some vintage models are faked very often, especially the Constellation. These fakes will often check all the boxes for the marking patterns described above, but some details will tell you it’s a fake.

You can find a detailed guide to authenticate Constellation cases at Omega Constellation Collectors, which is the resource for Constellations.

All of this might seem very complicated. Still, authenticate/identify some watches for the sport of it. As a challenge. After some time, it’ll sink in and become second nature.

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Showing 35 comments
  • Avatar
    Marco Bernardi

    Thank you for that great article.
    I have recently bought a Omega (Fab. Suisse) with 30T1 movement. The watch has a subsecond at 6 o’clock.

    On the bridge: 9179542
    The Case back (inside) states:
    Triangle: Logo and OMEGA
    Fab. Suisse

    I think Fab. Suisse stands for: made for French market
    The watch comes with a fantastic black dial with roman numerals in Art Deco style.
    I think the watch is from 1943 but I don’t know if case number and movement number fit together.

  • Avatar
    Clayton GUNNING

    Hi, I’ve recently bought an Omega Speedmaster Automatic Date circa 1991.

    Case number:

    Movement serial number: ?

    Short description:
    Omega Speedmaster Automatic Date

    Calibre 1155 – ETA 7750
    17 Jewel

    2 x case numbers: 1750043 & 3750043

    No unique identifying number on movement; Serial number on case back: 53638035

    99.9% of things written about Omega suggests this movement should be clearly marked with a unique identifier but there are a couple of articles that suggest Omega dropped the ball with this movement? There are articles suggesting the Omega 1155 is the crudest movement ever used by Omega. This movement was apparently only used in 1991 but I believe it was used in a LE of 500 pieces for the French Market celebrating the 1992 Albertville Winter Olympics.

    I’m interested in any information or view you might have on my watch.

    Please let me add I have had the watch looked at by two Omega trained watchmakers and neither is prepared to say the watch is fake or original.

    I have paid for an Extract from the Archives and am waiting for it to be processed.

  • Avatar

    Such a great article! Congrats on this excellent work!
    I have got a watch from 1964 according to the reference number. However the case doesn’t really match any 6 digits number… 14.90–62-SC.
    Any thoughts on what it could be?
    I can email you a pic if needed

  • Avatar
    Muzzamill Ahmad Javaid

    Dear, hope you are fine, same here. I just bought an Omega with 15 jewels movement and caliber number 30T2 is under the balance wheel. Its serial number is 10087475. The dial is with off center minute hand and seamaster is not written on it. The case back is with hippocampus logo and inside the case back its written:

    WATCH CO. (inside the triangle stamp)



    Please guide me regarding authenticity of this watch and from which year it belongs to

    • Melvin Hollenberg
      Melvin Hollenberg

      Hi, the 30T2 is an older movement and based on the serial number, this particular one is from 1944.

      However, the 135.007 is from the Geneve international collection that was introduced around 1969.

      So, I’m sorry, but this watch is not 100% original.

      • Avatar
        Muzzamill Ahmad Javaid

        Thanks dear, I am obliged for guiding me in expeditious manner

  • Avatar
    Edward FRankin

    I have a Omega “Automatic”purchased 5/71 at the Geneva airport, the face reads automatic and GENEVE . Recently the automatic date number stopped changing any suggestions.

    • Melvin Hollenberg
      Melvin Hollenberg

      It sounds like there’s something wrong with the calendar works. The watch needs to be overhauled by a watchmaker.

  • Avatar

    Great article and quite informative. I have two vintage Omegas, one of which I have pinned down, the second I haven’t yet taken to the maker to get opened, and a question on each.

    The first is a ’68 (26,9XX, XXX) Seamaster w/ date, caliber 565, on the original rice bracelet and original hexalite (man, those little “Ω” are microscopic!). However, the rear case stamping is “166.037 SP”, which I understand to be Geneve rear case… was this a swapped on part?

    The second is a 14K/stainless Seamaster De Ville, crosshair, date cyclops, and interestingly without a “De Ville” callout on the bottom of the dial (leading me to believe this is a 1960-1962 unit). The seller states it is an automatic with 19,800bph. Without opening it up, how can I confirm the movement? I have been winding it, but it is *not running* and I bought it as such. I don’t want to overwind it!

    Thanks gents, extremely informative site.

    • Melvin Hollenberg
      Melvin Hollenberg

      The 166.037 is a reference for a Seamaster produced between 1966 and 1970, so 1968 fits perfectly. That’s the original case back and watch.

      As for the Seamaster De Ville, without opening it up it’ll be a guess. Omega produced them both with manual and automatic movements. I believe that a model with an automatic movement should say so on the dial just below Omega. However, I’m not 100% sure that’s a hard rule.

      • Avatar

        Hello Melivin,

        Thank you for the reply! Excellent news on the 1968. She’s a beautiful piece and I plan on wearing while driving my 1968 Mustang fastback – just a perfect combination.

        I did indeed open my early Seamaster. I found that it is caliber 562, 24 jewel, which I believe makes it a non-US model (is it even a De Ville, without the dial stating the “De Ville” text?)

        The caseback states:
        ACIER INOXYADABLE (stainless steel?)

        WATCH CO. (inside the triangle stamp)
        FAB SUISSE
        SWISS MADE

        14770 1 SC

        C6 (inside of a “tombstone” stamp)

        It also has an unusual dial, which I haven’t found an image of online yet.
        It’s a crosshair, gold applique hour markers, “Ω” and “OMEGA”; AUTOMATIC is printed, “paperclip-S,” long “R” Seamaster font, but the minute track is inset of a white band all the way around the circumference of the dial’s face. It almost looks like a Geneve I found on the vintage Omega webpage, but even that wasn’t exactly it. (I know they made countless variations on these watches but I’m unsure if this is a redial or not!)

        In any case, I’m glad to report both are now ticking away happily!

        Thank you again.

        • Melvin Hollenberg
          Melvin Hollenberg

          Hi, you’re right. The 14770 is a Seamaster DeVille from the international collection from 1960 onward. I’m curious about the dial. If it’s possible, please send me a picture to

          • Avatar

            Yessir! Shot you an email with images of both watches.


  • Avatar
    Annie Slavin

    Good afternoon
    I have an Oméga Deville “Jeux d’Argent ” from 1974
    Serial number 35251916 for women. Would you know how much I can sell it?
    Thank you
    Annie Slavin
    561 672 4604

    • Melvin Hollenberg
      Melvin Hollenberg

      Hi, I’m sorry but we don’t value watches. The best thing you can do is to look for similar sold watches on eBay or other auction sites.

  • Avatar
    Per Christian Eggen

    Hi,i have apocket watch with the serial number 1533857. Can you help me date it ?

    • Melvin Hollenberg
      Melvin Hollenberg

      Hi, are you sure about that serial number? I think you’re missing a number somewhere or it’s not an Omega movement.

  • Avatar

    i have dial omega neptune enamel , around 39mm, which omega movements will be suitable for such dial size? thanks beforehand for attention

    • Melvin Hollenberg
      Melvin Hollenberg

      I’m sorry, but I’ve no idea. It depends on whether it has a sweep second or sub-second. Manual wind or automatic. I’ve seen the Omega 23.4 and the 352 mentioned.

  • Avatar

    My omega silver pocket watch,is in complete original working condition moment serial number is 7671138,i want to know the year of manufacture of my watch.

  • Avatar

    Hi, I got a Omega pocket watch with no 8838306. What might be the manufacturing year?

  • Avatar
    Richard Janes Cullis

    Love the site. I am looking at an “Omega” pocket watch with serial number 1350547. It would seem this should be from 1895 to 1902. The serial number is beside the winding wheel on the motor barrel bridge. My issue is that I can see the number just by opening the case whereas your site says I need to dissassemble the watch to see the number. Also only the only jewel evident is the balance end stone (I only have a photo of the movement). Does this sound like it could be genuine?

  • Avatar

    The mechanism is 6727172 ,how can I get more details about this a wristwatch of ladies.please

  • Avatar
    Paul C

    Hi I just purchased an Omega pocket watch with the serial number 11172450 and wondering the age please

    • Melvin Hollenberg
      Melvin Hollenberg

      Hi Paul,

      The serial number points to 1947 or 1948.

    • Avatar
      Sameer Kulkarni

      I got a pocket watch with all no 10078392. What might be the manufacturing year

      • Melvin Hollenberg
        Melvin Hollenberg

        Hi, the year would be 1945 or 1946.

        • Avatar
          Jeff Fregeau

          Learning watch expertise is for professionals only which is why I am seeking advice to have a 1962 Speedmaster watch properly serviced. Welcome any input.

          • Melvin Hollenberg
            Melvin Hollenberg

            Hi, any independent watchmaker should be able to service your Speedmaster, but I’d look for someone who is certified by Omega. He or she will know the proper procedures and will be able to order spare parts if necessary. Omega advices to replace certain parts during a service, for example, and an independent watchmaker will not be aware of this.

  • Avatar
    Chayal M L

    Great article.


    • Michał Kolwas
      Michał Kolwas

      Glad you like it!

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