NOT quite that simple, people...
There's a LOT MORE to it, using crystal specs (i.e. bezel openings and their compound, lengthwise, widethwise, or total absence of curvature...) which simply CANNOT be overlooked... This model was "guessed" to be the Harrington (vs. the Ivanhoe...) based on two IDs, and what Noel (vs. Gary, who better understands watches, crystals, etc. as he refurbs, repairs and resells them!) stated about the bezel opening... (i.e. That it only curved one way, vs. BOTH, as the Ivanhoe does...) The Regis was LATER FOUND, in a different catalog, I sourced AFTER the post... (And ONLY the Ivanhoe curves BOTH ways, as I clearly stated, and Gary mentioned!!!) Another party just bought the "compound curve" glass, who is a watchmaker... SO WHERE ARE I INCORRECT? Listening to the poster?!?
If you don't own any catalogs, then you don't LEARN TO see the "patterns..." And if you don't have/review at least a dozen different (G-S and BB alone, since they have the same Alpha shape prefixes, AND are/were the industry standard...) catalogs... then you have NO IDEA that the same crystal might fix a dozen of so models, from say four different decades... Nor that subtle differents in bezel curves for say a Gruen Curvex model (same bezel prooprtions!) means a dozen models+ that have different ARCS lengthwise, irrespective of what "aftermarket EFX" were inc. into the "option" equation, atop the bezel... (Vs. the UNDERSIDE, WHERE IT COUNTS...)
FACT: I am RIGHT 95% of the time, based on watch IDs in general... (500 and counting, a dozen brands...) I always CORRECT MYSELF on my VERY FEW misconceptions... and with the exception of a slew of fairly RECENT ads posted by Jerin, etc... (who I also basically "schooled," BTW...) where was this SITE, before we ID'd the VAST majority, of these models??? You don't even know, as you weren't HERE, before... (Hint: go to www.Archive.org 's "Wayback Machine... query this URL and have a look! That dates alone on 25% of the watches were 5, 10, 20 years OFF! Models, WHAT models?)
So what do I know that you don't? (PLENTY... Are where to start?!) And crystals are only PART of it... For instance... I instantly knew that "33 unknown" (or most any other 20s, 30s, 40s, 50s, etc.) case was mid 30s Art Deco... I ALSO often know who copied whom's designs from most top US brands... But we don't discuss other brands, except to leave "footprints" (in my case) for the GoogleBot, for instance... Child's play... That's what, three simple (but Paramount) examples of WHY I can figure these out... And I'm BEYOND TIRED of repeating myself... because I intended to ID 10,000 top US made vintage watch models from 1925- 1965 +/- and corner the market... and everyone else wants something for nothing... and simply ISN'T going to do their homework, or even INVEST IN the proper tools to further ASSIST...
GOOD LUCK, then! Scott