30 Pack 1mm Diamond Drill Bit Jewelry Beach Sea Glass Shells Gemstones Lapidary 30pcs. 1mm Set of 30 pcs. 1mm Diamond Drill Bits - 1/8 shank. Drills Beach Sea Glass, Sea Shells, Rocks, Marbles, etc. Used by Jewelry Designers for drilling clean holes. Fits drills, flex shafts and dremels. For Making Earrings, Pendents and Bracelets.