For Robyn, who will find it is easier than she thinks. We took these pictures in a hurry but I think they show well enough how I do it.
These are cheap bits but they work, I use the smallest one. The key is to drill down S-L-O-W-L-Y. And make a stone holder from scrap wood.
These stones probably came from Michaels craft store, maybe from their floral department. I think they are the kind you put in a jar to hold flowers straight up. The green ones are a fairly soft stone, the black is harder. They have some stones that look like flattened shiny marbles and I don't have any luck with those.
This is my set-up. The drill press isn't a real expensive one but the key to success is the wooden stone holder. The slot in the center is where you wedge the stone in to hold it steady. Susan dreamed this contraption up and it works great.
Mr. Safety has his gloves on and he's wearing his Mr. Safety glasses. You could use something else besides your finger to hold the stone in place but there's a limit to how girlie I'll get.
It is slow going, V-E-R-Y slow. I just use V-E-R-Y minimal fingertip pressure on the drill. When I do the black stone Susan sprays water on the stone while I'm drilling, but the green stones don't seem to need it. She's suggested oil (as in cooking oil) instead but I don't want to mess up the wooden stone holder.
This is what happens when you go too fast or get too close to the edge. Here you can see the narrowing down of the slot for the stones.
Drilled stones. And for you, Robyn, the metric side of the ruler!