Check out this great write up on the Gunther Multidrill System in the "Cool Tools" section of "Lapidary Journals Jewelry Artist".
“This is extraordinary. So wouldn’t it be great to use the drill press you’ve already got (like the awesome German-made Proxxon, or even a Harbor Freight on, for instance) and convert it for core drilling stone with a continuous water feed? Well my friends, now you can."
- Lapidary Journal Jewelry Artist