Yes, the CD bezel was
primarliy on the -1 to -3 subreferences. But remember these subreferences were produced within a short timeframe of each other (especially the last 5 subreferences)...and the "swop" periode could interact up or down with a subreference or more. I like to say that a -4 also could have had the countdown bezel and perhaps a -5. The -3 were produced from 1958 into 1960 and the 4 to 5 only first half of 1960. But a -7 subreference is produced mostly in 1961, so not likely that the old bezel was used on this!
Where did you read that?
That would imply that only cal. 500 (US export version) 2913's would have had the countdown bezel. I have seen no evidence of that. Is your 2913-5 a cal. 500 or 501? and serial? Is the OP watch a cal 500 or 501?
The best evidence I have (and not that good, since it's marketing - but there are NOT many original countdown bezels left on 2913's, so hard to research. Most 2913-1 to -3/4's have no insert or redone inserts and some the countforward) ... is the below snip from an old Omega brochure, where they "explain" the transition from countdown to countforward/elapsed time (and also the change from BA hour hand to BA minute hand).
I still think this change was global and merely a design change. Elapsed time bezel and BA minute hand are generally more useful from a diver/market perspective... I guess.
View attachment 309613
Click to expand...