Something I've noticed in my KS/GS research is that the crystal profile amongst different models can vary greatly, and it influences the overall "look" of the watch significantly. I find flat, flush-with-bezel crystals make the watch look more modern, while a domed or raised crystal is unmistakably vintage. I've developed a taste for the flat ones that look modern, as it makes some vintage Grand Seikos and King Seikos look timeless, like they could have been manufactured yesterday. This difference is particularly evident in comparing models pictured on thegrandseikoguy.com, a great resource.
For example, observe the utter flatness and flushness on this GS 6155-8040, utterly remarkable for 1974:
For comparison, here's a King Seiko from 1973 (5246-6010) with much more convexity to the crystal:
And here's one (6155-8000) somewhat in the middle, still raised, but completely flat and with beveled rather than round edges:
All this brings me to a couple of questions:
1) why do vintage watches commonly have a somewhat raised and/or domed crystal? There seems to be a progression in watchmaking toward gradually flatter and more flush-with-bezel crystals, with the domed-crystal-no-bezel evolving to the beveled-crystal-with-bezel (slightly raised), to the modern completely flat and flush. Was Seiko the first manufacture to be doing this? Their watches from the period certainly seem cutting edge, both figuratively and literally. Another reason I <3 them.
2) This question is for you King Seiko nerds out there. As mentioned, I'm partial to the flat and flush crystals. My personal favorite KS model, the 5626-7040 chronometer, as far as I can tell, has a crystal that is raised above the bezel, but completely flat and nicely beveled at the edges, similar to the "in-between" picture posted above. Like this:
So my question is this: were there different crystal profiles throughout the model run, because if so I'd prefer the most flat one.
2a) follow up question: if I wanted to buy a beat up King Seiko 5626-7040 and modify the crystal to be more flat, is that possible?
Anyway, I love these vintage King and Grand Seikos and look forward to your response.