I have never used a generic crystal, I have always used genuine replacement parts. I have a watch with a broken crystal that I would like to replace with a generic mineral crystal. The reason is because I am not very experienced and have ruined gaskets in the past (crimped them). I haven't found a way to purchase JUST the gasket for a genuine crystal, they only seem to sell the gasket and crystal together. If I use a generic crystal and gasket, I can order as many extra gaskets as I want. According to my measurements, the case opening has a diameter of 25.6mm at the bottom. It looks like the opening gets smaller about halfway down, so the diameter at the top might be slightly more. The original crystal was broken, so I can't get a measurement of the diameter, I could only get that it is 1.5mm thick. The original gasket was an L-form gasket. So here are my questions: I can't find an L-form gasket with an OD of 25.6mm, I can only find one with an OD of 25.5. I CAN find I-form gaskets with the correct OD, but I am worried that using one will allow the crystal to sit too far down because there is no ledge on the gasket. Should I just use an I-form gasket with OD of 25.6mm and not worry about the crystal going too far in? Will it be noticeable? Should I get an L-form gasket with OD of 25.5mm but squeeze a crystal that is 0.1mm larger than the ID of the gasket in hopes that the gasket can stretch that tiny bit and create a tight fit? Should I just buy genuine replacement parts (I think about $15 for crystal and gasket) and just try to not screw up the gasket? I do have the original gasket (in pretty good shape) that I could use if I mess up the new one. Thanks for the input!