... : HP, diamond coated for grinding, engraving, carving on metal, wood, bone, jade, PVC, glass, stone ... PFM, chrome & ceramic materials;3. Also for grinding and engraving on metal, wood, bone, jade, PVC, glass and stone ... as glass drill bit, diamond drill bit, jewelry drill bit and engraving bit.4. 3 grits for selection.About Us ... information. HP conical shape medium grit coating diamond engraving tools