But ceramics vary widely in their properties, and this is one you could
only
learn from experience, unless you trip across someone else's account of how
it's done -- from experience.


When I worked for Dow they brought in a ceramic they wanted me to try and
drill with the ultrasonic drill we used on glass. After 2 days drilling and
wearing out 4 bits I was able to make a 3/16" wide dent about 1/8" deep in
it.

This stuff had a Rockwell rating of 97 for hardness!

Randy Hansen
SC Glass Tech.
Scam Diego, Comi-fornia