Hello, this is my first post on this forum. I have an Omega 320 chrono, that is missing the bezel. I intend to have one made. I've been looking on and off for a proper Omega one, but realise I'm not going to find one. Before I get a bezel made, I'd like to know what was the original size crystal. I have various Omega reference books here, but they don't cover the non-water proof cases. The case reference is 2463. I know from the serial number it dates from 1957. Thank you in advance.