Titanium Coated 1mm Diamond Drill Bit Set 30pcs. Jewelry Beach Sea Glass Shells Gemstones Lapidary 30 Pieces High Quality Titanium Diamond Coated Drill Bits 30 pieces 1 Size - 1mm Total of 30 pieces Fits drills, flex shafts and dremels. Used by Jewelry Designers for drilling clean holes on Beach Sea Glass, Sea Shells, Rocks, Marbles, Stones, etc. Make your own custom earrings, pendents and bracelets.