Just go to your local home improvement store, and go to where they sell ceramic tile. With the ceramic tile tools, you should see tile drill bits. They should drill though the hardest stones with relative ease. I would use them in a regular drill though, because if your dremels speed is too high, the bit will get very hot, and lose it's temper, and break. Drilling in the sink with cool water dripping on the rock and the bit will prevent this entirerly. Hope this helps! Been a cannabis.com reader for a couple months... but I registered just so I could help YOU! and BTW... the tile bits work wonders for drilling holes in ceramic and glass vases to make them into bongs! :bong: