What do I use to drill a hole in a cabochon? I can't find anything to go through.
Use a small rotary tool with diamond-coated steel burrs to drill holes in your cabochon. The key is to keep the cabochon (not the drill!) under water. This will keep the piece from breaking from the excessive heat produced by the drill as well as keep the dust from clogging the drill bit.
Warning: It is important to wear protective eye wear and work slowly and carefully to ensure safety.
Fit the rotary drill with a fine drill bit. Place a scrap piece of wood into the bottom of a shallow pan (the wood will help stabilize the cabochon while you're drilling as well as prevent you from drilling through the bottom of the pan.) Fill the pan with water to above the piece of wood. Place the cabochon on top of the piece of wood then put on your safety glasses.
Start up the drill, stabilize the cabochon with your non-dominant hand and begin to form a pilot hole with the rotary tool. Until the pilot hole is started, the drill bit will want to dance around on the smooth surface of the cabochon so work slowly.
Once you've established a pilot hole, drill further into the cabochon. Change out the drill bit to the next size up and drill a larger hole. Continue with the drilling process until you have a hole to the desired size and depth.
Do not discard the water down your household drain as it could clog your pipes. Dispose of the water outside in the yard or pour it into a bucket. The water will eventually evaporate leaving just regular dust.