When you want to drill a hole through a ceramic plate --- perhaps to insert a mechanism and turn the plate into a wall clock --- you need to use the correct tools and techniques to avoid damaging the plate. Even though ceramic is a tough and hard-wearing material, it notoriously brittle and if you are not careful when drilling, your plate will chip or crack. When drilling any ceramics (as well as glass, porcelain, marble, granite, stone and some other materials), a diamond drill bit is essential for successful results. Don't be tempted to use any other kind.
Cover the place on the ceramic plate where you want to drill a hole with a strip of masking tape, then mark the exact point for the hole with a pencil dot on the tape. The masking tape will prevent the drill bit from slipping when you begin drilling though it.
Place a flat piece of scrap wood on your work bench or the surface underneath the plate. Position a G-clamp around the wood and plate, place a small piece of scrap wood between the top of the clamp and plate, then screw the clamp closed to hold the plate firmly in place. The pieces of wood protect your work surface and the plate from the pressure of the clamp.
Fit your drill with a diamond bit of the appropriate size for the hole you want to drill. Set the drill to a speed of 100 to 200rpm.
Recruit a friend or family member to spray the drill bit with cold water as you work when you are ready to drill through the plate. This prevents the bit from overheating.
Position the drill bit over the pencil mark on the masking tape and hold it at a perfect right angle to the plate. Begin to drill slowly and steadily without applying any additional pressure. Don't be tempted to speed up or press down as you work, just take your time and let the drill bit do all the work.
Stop drilling as soon as you feel that you have gone all the way through the plate and into the scrap wood underneath it. Un-clamp the plate, wipe it clean with a soft rag and remove the masking tape.
If you are worried about drilling through your good plate, practice first on an old plate made from a similar kind of ceramic material.
Wear safety goggles while you work.