How do I drill a hole in a gemstone already polished.
Set up a variable speed rotary drill or flex shaft (one with foot pedal control is best) and fit the collet with a diamond drill bit. If possible, start with a drill bit that is smaller than the finished hole size so you put less stress on the bit, the drill and the stone. Set the drill or flex-shaft into a drill press if you have one. Prepare a shallow dish with water and if using a drill press, place the dish on the base of the press otherwise just have it available in front of you.
Mark the hole placement on both sides of the stone using a permanent marker, then set the stone into the water to ensure it is not so deep the water overflows, yet is deep enough the water can help to flush the hole as you make progress with drilling and keep the drill bit free from debris.
Put on a dust mask to protect you from inhaling any dust particles that may become airborne while drilling. Turn on the drill and bring it toward the surface to begin drilling the stone. Work slowly at first so you can adjust to the speed, as well as keep the bit in place as it begins to break through the surface of the stone--since your stone is already polished, you want to avoid having the bit skitter across the surface.
Continue drilling, putting gentle downward pressure on the drill, allowing the bit to do its work yet not forcing it into the stone. Flush the forming hole and drill bit to remove debris and to keep the bit and stone cool. Continue drilling and flushing the hole and drill bit until you reach about halfway through the stone. Turn the stone over and begin drilling toward the other side of the stone and work until the holes meet in the middle. Once the hole is drilled through, increase the drill bit size and open the hole up to suit your needs.
If needed, tumble the stones in a tumbler with tumbling media or use the appropriate polishing discs in a JoolTool to polish the surface back to the original shine.
- Tammy Honaman, Author, Jewelry-Making Expert and Educator