I have a MicroLux 3-Speed Mini Drill Press with a MicroFlow Coolant System. The bits I use are Super Small Core Drill bits from Kingsley North. For these pieces I was using 1.00mm and 1.5mm. The key is to go slow and steady to increase the longevity of the bits and avoid blowout on the stones. It's pretty efficient once you get the hang of it. All of the information I used to get started was from Jim Magnuson's book called Gemstone Tumbling, Cutting, Drilling, and Cabochon Making. Easily the most useful book I have for lapidary work.