I have been buying small caliber26.5 and the like to build up some spares for servicing my Medicus and Naiads and decided to do some sorting out and labeling today.
Came across this movement and dial, never looked at it closely before. Firstly the bright tooling drew my attention then the Adjusted 3 Positions and finally the most peculiar Click stop to the spring barrel.
Anyone have any idea what sort of watch this started life as?
As an aside I gave it half a dozen winds and it was off working - still is

 

Forgot to mention the cal - looks like 23.7ST2

 

Cal 23.7 was created in 1918. The t2 version (2nd transformation) is the biggest production, although it was created in 1926, the same year as the 26.5 SOB. 23.7 was widely used in the men's wristwatches until the cal 26.5 SOB replaced it in round watches (some round cases were produced after 1926 with some 23.7. It was then kept, in particular in rectangular and tonneau / cushion cased men's wristwatches, I guess because it allowed narrower cases than cal 26.5. 23.7 was also used in some women's wristwatches.
When cal 20F was launched in 1929, Omega had two more modern calibers, the 26.5 for round cases and the 20F for rectangular/tonneau. In 1931 Omega granted a special discount to its retailers on 23.7 which apparently didn't have success anymore.
The bright finish of your caliber is not unusual for this reference, and the mainspring click is the same as was used 26.5 SOB (it was replaced by a different one on 26.5 SOB T1). Two watches references with a 23.7 ST2 are, IMHO, very interesting for collection : the armure (ref MG957) from 1929 and the Golf (ref AR 909) from 1931.

Could you please give the size of the dial you pictured, it seems big for a wristwatch of that period. It coud be a woman's Pocket Watch.

A couple of catalog pages with some 23.7 :

1925 :


1927 (after the introduction of 26.5 SOB) :


1933 (still one men's ref in gold) :


and a couple of mine :
The armure :


A couple of tonneau cases :




A rectangular one :


I'm still looking for a golf in good condition....

 

Hi

The dial is exactly 31mm Diameter, Crown at 3 and Sub Sec at 6

You seem to have some knowledge regarding these early small watches - I have made a post today in the Photographic Forum, perhaps you would have a look at it as possibly you may have seen this model. Forum title is "Roman from France"