A couple of questions please.

I was wondering what the numbers on the lug backs of some vintage 30s-40s Omega watches mean or what they are for?

Also when did omega start using the reference number inside the inner case back? I believe late 1930s but would love to hear what you guys think.
Thanks Michael

Hi Michael,
The numbers are reference for one case and its caseback so that watchmakers don't mix them (I guess at the factory and during service). I've seen on some T17 the last two digits of the caseback number ebgraved on the case (Inside bteween the lugs). Having two of the same model, I tried to switch casebacks without success, they didn't fit in without using force, so I think casebacks and case were adjusted in the factory, even during this era were all parts were supposed to be exchangeable.

The earliest reference numbers inside the caseback I've seen were 1944-45. One famous example is the 1944 RAF ref 2292. I've seen this same model with either the 2292 reference or a 10million serial so they must have co-existed. I have one exception with a 26.5 circa 1928, that has the model ref (816) instead of the serial engraved Inside the caseback. I have always suspected that it was a service caseback, without certitude however.

Yann

Thank you Yann.
Pm sent