diamond drill bit: HP, medium, diamond coated for grinding, engraving, carving on metal, wood ... 1. Most modern galvanisation process, safe and lasting diamond coating, optimal working results;2. Ideal for shaping ... stone carving, can be used as glass drill bit, diamond drill bit, jewelry drill bit and engraving bit;4. 3 grits for selection.About ... sales person for more information. HP diamond drill bit