I am a lapidary, and I also make jewelry, so I have several solutions, trim saw being the most likely. If you only have a flex shaft, there are diamond wheels that will do this, just be careful and use water as a coolant. You may not have to cut a continuous groove. That depends on the shape and how you want it to look. The thinner the bezel material the better as it will be easier to roll. Keep in mind that rolling could cause the crystal to chip if you are too aggressive. Following should be a picture of a piece of Tiger Iron that I set this way. My wife wears it a lot and you can see some dents in the thin bezel material. If you look closely, you can see one edge of the groove. My goal in this piece was not to use glue. I have used glue in the past, but it seems like cheating.