The strange case of the missing serial numbers

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Mark020

·Sep 30, 2024·not the sharpest pencil in the ΩF drawer

During my research I found a number of UG's with a reference number but without a serial. There are a number of possible explanations:

• Prototype: I have never seen a UG marked as prototype so probably they were never marked as such
• Sample: so used by the sales department to show to retailers
• Forgotten: my - more general - theory is that the case producers did the numbering. I would assume that clear errors like this would be rectified
• Replacement caseback: but why not add a serial
• Removed: almost impossible to do (but perhaps doable with laser welding)

Curious to hear opinions!

The examples I found:
https://marketplace.watchcharts.com...-moon-phase-chronograph-watch-ref-22538-22536 CB probably legit although the inscription on the inside is not the best I've seen. Font of the serial is off.

Strangely enough another ones exists: https://uhrerbe.com/unt/33019-universal_geneve_tricompax.html

https://www.liveauctioneers.com/item/65817824_universal-geneve-gold-tri-compax-chronograph-wit The '1' may be an indication for a replacement

https://omegaforums.net/threads/nice-ug-on-chronocentric-whats-the-consensus-on-prototypes.56763/

Thread 'Nice UG on chronocentric... What's the consensus on "prototypes"?' ·

Hey guys,

I've seen this ad on chronocentric today, and it peaked my interest. Unfortunately it is really too small for me at 34mm, but the dial looks awesome.

The seller says that it is a...

MaiLollo · Apr 23, 2017

https://omegaforums.net/threads/zenith-compur-cal-136.29527/

Thread 'Zenith Compur cal 136' ·

So I'm back on my on-again-off-again Compur search, with more questions for the Zenith gurus (sorry guys!)

This one pops up. As far as I can tell:

- dial looks appropriately patinated and...

NT931 · Sep 19, 2015

https://www.bonhams.com/auction/225...compax-case-no-22536-movement-no-22081-1940s/

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https://omegaforums.net/posts/2398990/

Mark020 · Sep 21, 2024

This is an interesting one. 100% legit but no serial. Not the first time I've seen it: https://www.ebay.it/itm/335582659204

Close movement serial here: https://watchcharts.com/listing/560...m-movement-chrono-radium-dial-waterproof-case for comparison

Edited: Sep 30, 2024

 

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gilb12

·Sep 30, 2024

Very Interesting Mark! I think 90 % of examples are between 1 and 2

 

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Mark020

·Oct 3, 2024·not the sharpest pencil in the ΩF drawer

And another one: https://dumarko.com/collections/vin...ntage-universal-geneve-watch-rare-swiss-watch

 

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Mark020

·Mar 18, 2025·not the sharpest pencil in the ΩF drawer

22250 https://antique-picker.com/?pid=145817147

 

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Mark020

·Apr 21, 2025·not the sharpest pencil in the ΩF drawer

Another 22536 https://www.analogshift.com/products/universal-geneve-tri-compax-2

 

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Larry S

·Apr 21, 2025·Color Commentator for the Hyperbole.

My 124104 Compax. Normal markings on inner but no SN … inner case photo from when I bought it from a member here. I’m out of practice with my case knife. Obviously a correct watch so I’ve been puzzled as well.

 

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bgrisso

·Apr 21, 2025

Mark020

Another 22536 https://www.analogshift.com/products/universal-geneve-tri-compax-2

I assume all the examples you have posted in this thread you have verified there is no serial on the interior caseback? (I haven't click on all the links to see additional pics).

 

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Mark020

·Apr 21, 2025·not the sharpest pencil in the ΩF drawer

As far as possible yes

 

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Larry S

·Apr 21, 2025·Color Commentator for the Hyperbole.

I’m in the “forgotten” camp.

 

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Mark020

·Apr 30, 2025·not the sharpest pencil in the ΩF drawer

And another one (ref 21320): https://www.chrono24.nl/universalge...40171840.htm?searchHash=230953fd_gDibIx&pos=4

 

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Mark020

·Jun 12, 2025·not the sharpest pencil in the ΩF drawer

Another one: https://www.ebay.it/itm/157060478467 Ref 22502. Fortunately the movement serial is visible: 246.164.

A close sibling (246.160) was sold by Iconeek but unfortunately no pics to be found any more. Serial of that one was 1.106.012. A close serial of that one (1.105.968) is :https://www.catawiki.com/en/l/13008...-register-12-hr-register-tachymeter-stopwatch

Comparing the casebacks shows that the ebay one has a later CB so we may consider it a service one. Case solved?

 

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magana_manuel

·Jun 12, 2025

I'm bidding on that one from eBay, as long as it stays at a reasonable price.

 

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martinc

·Jun 13, 2025

Mark020

Another one: https://www.ebay.it/itm/157060478467 Ref 22502. Fortunately the movement serial is visible: 246.164.

A close sibling (246.160) was sold by Iconeek but unfortunately no pics to be found any more. Serial of that one was 1.106.012. A close serial of that one (1.105.968) is :https://www.catawiki.com/en/l/13008...-register-12-hr-register-tachymeter-stopwatch

Comparing the casebacks shows that the ebay one has a later CB so we may consider it a service one. Case solved?

Based on the case shape, I doubt it’s a 22502.

 

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Larry S

·Jun 14, 2025·Color Commentator for the Hyperbole.

Could UG have supplied service casebacks that the dealer could stamp with the reference number? I suppose case knife mishaps could have been a common occurrence?