I am new here. Can anybody tell me why on a 50's or 60's Seamaster why most have one set of #'s inside the caseback and some have two sets of #'s? Also what do the letters mean? For example A caseback says 11488842 and then below it 2757 SC?

Thanks

 

SC designates a center-seconds reference, i.e. with a sweep seconds hand instead of a sub-dial. However, some of the letters following reference numbers seem to be pretty obscure.

Some early case-backs have case serial numbers in addition to the reference number, but I'm not sure that case serial numbers really extended into the 50s, so the second number might have a different meaning. Perhaps you could show a specific example if you want to understand it.

 

If you scroll to the pic of the inside of the caseback you will see what I am talking about https://www.1stdibs.com/jewelry/wat...aster-automatic-wristwatch-1952/id-j_9168442/

 

2975 SC is the reference number and 11488842 is the case serial number. Omega stopped giving serial numbers to cases in the fifties.

 

Yes, in that case, the 11M number is a case serial number as indicated in the standard chart. I already explained the reference number and suffix for that particular example. If you have questions about a suffix other than SC, you can start another thread. You will sometimes see a caseback with two reference numbers, which indicates that the same caseback was indeed used for two different references, e.g. a center seconds reference and a seconds sub-dial reference.

 

That's good information. Thank you so much!

 

Here is another which claims it is from 1960. https://www.ebay.com/itm/Fine-Vinta...424352?hash=item3b464b8320:g:PhsAAOSwxW9eqHs~Purchases made through these links may earn this site a commission from the eBay Partner Network

Although, I have a strong suspicion this caseback does not belong with this watch. Does the "E" denote that it is electronic?

 

The caseback is gold filled, the mid case appears to be stainless, but I think it's all due to lighting.
This is an American produced case made by Jonell Watch Case Company of Long Island New York.
The E has nothing to do with electronic, it's probably an inventory number, the model number is L6288.

The watch has significant rotor bush/axle problems, I didn't look at anything else.

 

Please excuse my lack of experience but....E28508 is the lower # @JimInOz but, the 1st three #'s 285 of 28508. It is my understanding (perhaps mistakenly) that "2" denotes it is a "Gents Jewelry Watch". "8" denotes it is a "Electronic Chronogragh" and the "5" denotes it is a "Water Resistant" . This as per the attached photo of Codification. I am new and trying to learn. If I am missing something please let me know.

The watch is listed as an "Automatic".

 

I think you are looking at a chart for more modern reference numbers.

 

The number beginning with E is a case serial number and nothing more it has absolutely nothing to do with the type of watch. Furthermore this is, as previously noted a US made case so any reference charts you might find are meaningless since they will always reference ROW watches, not US cased pieces.

 

Omega has had 3 or 4 reference systems in the past 70 years, that is not the era for the watch you are asking about.

 

I appreciate all of the replies. As I said I am trying to learn.Thank you for that information. Where do you find information on those reference systems and the specific period they cover?

 

Some folks have a copy of the Omega reference book A Journey Through TimePurchases made through these links may earn this site a commission from the eBay Partner Network or perhaps Moonwatch Only while other forum members have written their own books. The rest of us have seen hundreds of watches over the years and have essentially memorized the Omega Vintage Database. Hang out here long enough and you'll acquire all that knowledge for free. Collecting vintage watches is all about patience, research, and the hunt for that special watch (or three) to call your own.

 

well there are 3 easy to see systems... 1 looks like 2347, one looks like 145.022, the other 345.043.4234 or similar...