Hi. I have a Seiko SKA505 Kinetic watch that I haven't worn for years due to a large scratch on the hardlex crystal. I removed the crystal last night, measured it, and was planning to order a sapphire replacement online. My issue is that the original hardlex crystal has a diameter of 30.9mm, which is an uncommon size for ordering a replacement. Plenty of online places sell sapphire replacements in 0.5mm size increments, but sourcing something that is 30.9mm is difficult. The only source I have found selling this size charge US$16 for delivery to Australia, which on top of the US$28 for the crystal makes the whole thing uneconomical (Aliexpress sells similar crystals in 0.5mm size increments for less than US$15 delivered to Australia). I have two questions: does anybody know somewhere I can economically source a 30.9mm sapphire crystal online? Or alternatively, would a 31mm crystal fit OK in my watch? I have no idea about tolerances for fitting watch glass, so am not sure how crucial a 0.1mm difference in size is. Any advice or recommendations is appreciated!