zOwie Omega Discussion Forum

: Greetings from the other (Heuer) side. I have a mystery that I am
: hoping someone can help me solve. Its regarding my Seamaster
: cal. 321. I would like to know if anyone can confirm the case
: reference number for this particular watch. The movement serial
: number is 17764xxx which places it around 1960/61. It came with
: a caseback numbered 105.005.65 which is later than the movement
: and I have a suspicion is incorrect. Any assistance will be much
: appreciated.
: regards
: Paul
: www.heuerworld.com

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Omega's serial number charts are not to be relied upon as accurate to within more than a few years. There are a variety of reasons for this.

Omega set aside serial number sequences for production of a particular calibre, and did not issue serial numbers as watches left the factory. Slow moving calibres may have been sold years after the typical date range for serial numbers.

Lemania movements, not manufactured by Omega, as the 321 was, add another twist. These movements would logically have been numbered prior to delivery to Omega, and might therefore be out of the typical numbering range.

Some have put forth the story, which I have not seen confirmed, that Omega bought what proved to be a ten year supply of calibre 321s in 1959. This supposedly explains how Speedmasters with calibre 321 are consistently out of sequence with the "normal" range of serial numbers and dates of production. This theory seems flawed by the fact that serial numbers from 16xxxxxx to 26xxxxxx appear on calibre 321s from 1959 to 1969.

Seamaster chronos were not apparently widely sold and might therefore have another reason to lag a bit behind the typical serial number range.