For how often the cyclops is brought up, it’s really one of the worst ways to tell given that the crystal is the most replaceable part of the watch. You can tell because it’s a stainless steel day date, because of the overall terrible quality. Especially with older Rolexes with acrylic crystal the cyclops can be worn down to where it actually magnifies less.

Thinnest would be a late 60s Timex Wafer Thin and my thickest a mid 60s Squale Master 1000 meter dive watch with a thick ass dome crystal on top of an already beefy case.