For earlier models like the 1863 on the 3572.50 reference, the glass is replaceable.
It is friction fitted with a gasket. The gasket is made of hard plastic and is only made for 1 use. It is much like the front glass crystal. No glue is used I believe.
Here is an older post where the question of replacement of the caseback glass is talked about: https://omegaforums.net/threads/3752-50-caseback-crystal-replacement.47138/
I’d reckon the same process is used on the current models but I think @Archer can offer the final answer.
Combination of the two - the seal is not "L" shaped and is just a straight sided seal. But the bottom of the crystal seats up against a lip on the steel case back.
Thanks much for clarifying. I read everywhere how very hard, but extremely brittle synthetic sapphire is. So, I’m a bit surprised the gasket does not seat under the crystal/on top of the lip, as I would think that would mitigate shocks through the crystal somewhat.
Very few Omega crystals that I have come across use the L shaped seal. When they do, it is typically on mineral crystals, so older models.
So most crystals seat right on the case (steel, Ti, gold, etc.). In fact, one thing I was taught at Omega in training was that once the crystal is pressed in, you leave it for at least 10 mins, and the seal will cause the crystal to rise up a bit. You then go back and press it in place again, and you listen for the click of the crystal seating on the case - here's a video of that sound - turn it up:
I don't think I've ever come across a crystal that was chipped on the underside, where it seats on the case.
