Crystal size of Omega Automatic Geneve Seamaster 1967 cal. 550/552

Hi guys,

It has come the time to bring a new life to my old grandfather's watch - Omega Automatic Geneve Seamaster (probably manufactured in 1967, cal. 550/552). The crystal has lots of deep scratches and I would like to replace it with a new one but original, Omega signed. I will ship the timepiece to a watchmaker in аnother city (fine watchmakers are a rare thing around here) and he damands me to buy the new crystal myself because he has in stock cheep spare replacement crystals only. I did some research on eBay and it occurs that there are some differences in measurements (29,60 mm, 30 mm, 30,60 mm, 31 mm, etc.). Grandpa's crystal measures roughly about 30 mm but is there a way of being sure how much exactly without the watch being opened? Of course, that's a clear solution but I will lose some time. I would appreciate some opinions here, thank you.

A link to the vintage Omega database:
https://www.omegawatches.com/planet...ache=1&cHash=36e1dba07e19cc6ceeaa3b902462b6a7

Example photo:


Regards,
Dimitar

Thanks, Jim, it should be 165.0037 (according to Omega database) and maybe crystal type PZ5028. Well, I guess I really have to send it to the watchmaker first.

Cheers,
Dimitar