I had a nice case that needed a crystal so I ordered two of them, one for stock. I worked for about an hour total and then cracked the crystal. Not being too concerned because I had another I tried to install it and shattered it. So I ordered a third. (Now I'm into this thing $30.00 and still don't have a crystal for it.)Measurements are matching but crystals are not snapping in. So I try something I learned in Science class years ago. Put the crystal in the refrigerator for an hour. (The next step must be done quickly.) Using your alcohol lamp heat the bezel. JUST warm it, don't make it too hot. The metal will expand and you can snap the cold crystal right in. Cold causes contraction and heat will cause expansion. When they both come back to ambient temperature all is well.

heat and cold could also cause the crystal to shatter.

I am beginning to learn to the method of, "If it don't snap in then try to sand it a little or get a smaller size and as you said cement it in. I have a ultraviolet lamp made for crystal glue. Also remember I said the refrigerator for an hour. Most refrigerators are set about 40 degrees which is not really very cold. And the bezel can easily take a temp of a hair dryer or alcohol lamp. Restrain your self and don't get carried away. Common sense should always be applied.