Omega supplies service dials for a 321 speedmaster, which is pretty unusual service for a company to continue to supply parts for an item manufactured at least 45 years ago. This modern dial is easily spotted as it has Superluminova Markings. A simple lume test will show it. (Expose to strong light for a few minutes, then switch off and observe – a strong glow indicates Superluminova)
It would appear Omega has manufactured a variety of “Service Dials” for 321’s that were used throughout the 1960’s and later. These pre c1994 (my estimated date) dials are not the same as the 321 service dial available today.
Here are some examples of Calibre 321 Speedmasters with Omega made, service dials. These dials vary from original specification but are clearly Omega made, and made for the Calibre 321. When fitted these earlier dials still reduce the overall value of the piece, but not as much as superluminova’s.
They can easily be spotted as they are tritium, some with T marks of wide spacing, some of narrow (similar to early 105.012’s) and with painted logo dials instead of applied metal logos.
I believe the dials pictured above with no T marks are still Tritium, as they do not glow comparably with the superluminova. I cannot explain this.
Since writing this, I have come across several short indices, AML dials with 321 feet. Here are some examples:
Here is another example of a service dial owned by a member of OmegaForum.net: