After many, many, years in the business, a couple of weeks ago, together with my friend Gino I started to wonder which has actually been the earliest serial number for caliber 321.
At first sight, one might think that it should be about 10.8 millions, since this number appears on many Omega technical sheets:



In fact, if we make reference to the picture below, it appears clear that the serial number 10,388,005 does not make reference to a proper 321 - different from what is stated in the certificate, but to a movement which can still be considered a 27 CHRO 12:



The movement is not copper colored and does not bear the engraving 321 on the balance cock.

However, this remain the case also for a 11,497,555 movement - see the picture below - which is still very much the same as the one in the 10 millions range.
A proper 321, copper colored and with all the correct engravings, is shown on the right side of the same picture and bears the serial number 12,976,101.



It seems therefore likely that the earliest 321 serial number should fall in the range 11.5 - 12.9 millions.

Where, exactly? Can any evidence be provided to narrow this range?
Any contribution would be very welcome.

 

Maurice... ask Gino to show us his white 321 and i'll show him another

Plus a couple refs. to mark the transition.

/F

 

Thank you: unfortunately it is a difficult topic. And marks a difference between real Omega experts, if any.

 

Hello,

From our research to write the book we state that:

- the earliest 27 CHRO C12 is 9.390.xxx but there might be earlier unconfirmed number (the earliest in our collection is 9.391.213)
- the earliest OBSERVED movement with 321 engraved is 11.497.921, color is steel steel. The production of this batch of movement is dated January 1949
- the earliest OBSERVED movement with copper-colored 321 is 12.490.252. The production of this batch of movement is dated first half of 1951

Of course the numbers represent a rough observation and will be fine-tuned with time...

 

Thank you very much.

What a coincidence: the earliest 27 CHRO C12 I have ever dealt with is in your collection!
It is a very remarkable specimen since it features all the original characteristics of the project: straight minute jumper spring, bimetallic balance wheel and no antishock.



With respect to the earliest movement with 321 engraved that you observed, 11,497,921, it is interesting that the production of this batch of movement is dated January 1949, while the one that I have shown previously, 11,497,555, has no 321 engraving and results, albeit with a very tiny difference of only 366 units, produced in May 1947, twenty months earlier!

Finally, would it be possible to show a picture of the earliest observed copper-colored movement, that is the one with serial 12,490,252?

Thank you very much again for your contribution.

Cheers,

Maurice

 

Sei Maurizio che ho incontrato a Aosta?

 

I am afraid not.

 

There are many subtle differences in apparently identical calibers that go well beyond the knowledge of collectors and experts. Nevertheless, the evolution of calibers is a fascinating topic, especially in the case of mass producted and popular calibers, as 320/321.

 

I do believe that the 10 Mill 321 etched movement shown in old technical sheets is a genuine specimen.
If the cal. 321 was released close to the date the serial corresponds to, i do not know, but i believe that an updated for the observed specimens is in order.

Here two specimens with early serials:



Cal. 321 with a 11.497.685 serial.



Cal. 320 with a 10.830.624 serial. I have observed others in the same range but i can't seem to find the pictures.
The bicompax specimen was sold on OF a while back.

In relation to the above movements, i have also observed that in the range of 9.3 and 11.4 Mill serials, a number of white chronograph movements have been delivered. At a first look, it may not seem important, but what is actually striking is the variety of movements available: 28.9, 33.3 (possibly late stocks), then 27 Chro, 320 and 321, all white. Add to these pocket watch chronograph movements too.
What is even more interesting is that all these calibers where available in the same time, especially in the 10-11 Mill range. Cases observed have either in 3 or 4 digit ref's.
Above mentioned movements were totally replaced by the cal. 320/321 copper finish starting with 1950.

A very prolific period in the Omega history.

 

Thank you very much for your contribution.

If we decide that white calibers are to be considered fully mature 321s, I agree.

Interestingly, in my picture showing the serial 11,497,555, just a few units younger, an engraving pertaining to 27 CHRO can be seen under the balance wheel. It could be thus inferred that the full transition - limited to engravings - from 27 CHRO to 321 might have taken place in the range 11,497,555 - 11,497,685.
However, it also seems from your contribution that - again with reference to engravings - the 320s have fully matured at least about the serial number 10,830,624.
This is not surprising, given that the caliber was originally born with the hour recorder.

Nice observation: many chronograph calibers exist in the narrow range from 9.3 to 11.4 million serials.

Here is a picture of a 27 CHRO marked Lemania, which could sign (if unmolested) a transition from the original caliber 9,391,213 by speedy4ever to the newer version with an uncut balance wheel.

 

I just found in my archives the following movement with serial number 12,490,122:



This means that, according to your source, the earliest copper colored 321 should fall in the serial range 12,490,122 - 12,490,252.

Now, it remains to find a picture of a copper colored 321 about 12,490,xxx serial number!

Thanks a lot,

Maurice

 

Any additional contribution? I hope we have not gone too in depth.

 

I am still compiling my researches and there are a few more novelties on the matter.. especially on the circumstances of the appearance of the fully mature 321.
As for the earlier copper finish specimens, they seem to be rare to find between 12 and 15 Mill specimens. Specifically, i haven't found any 13 and 14 Mill serials in my archive.

It is rather a complicated subject if one doesn't know what to look for.

 

Thank you for your interest and cooperation. My impression, too, is that not a large number of specimens has been actually produced betweeen 12 and 15 million serials. However, I am able to show you a 13 million and a 14 million serial:

Indeed. But it is also a very interesting subject: please bear in mind that for about twelve years (1950-1963) copper colored 321s do not seem to have undergone any significant change, while between the second half of 1963 and the end of 1968 they changed quite significantly.

At the moment, I am still looking for a picture of a copper colored 321 about 12,490,xxx serial number.

 

I've got this 13x serial copper finished one in my collection:

 

Yes, it is more complex and most likely the new improved system was introduced to reduce eventual delays.

Valjoux or Venus did not improve their jumpers, sign that they never had problems with it... however, the part is now usually affected by rust in many, if not most pressed in back case specimens.
Omega/Lemania takes credit here.

 

Nice watch, thank you. Is the same shown in your avatar?

 

Notice that in its Lemania based movement Patek kept the original minute jumper spring: