CNBTR Coated Jewelry Drill Bits 2.0mm Dia Marble Glass Ceramic Hole Saw Tool Pack of 20 Excellent for making clean and accurate hole on glass, tile and marble. Shank Diameter: 2.3mm/0.09" Dimension: 2.3 x 43mm/0.09 x 1.69"(Dia x L) Start your hole diagonally, make a round trace and then hold drill straight. This diamond coated core drill bit removes a complete circle from glass, tile, marble, granite, ceramic or other materials and needs water for lubrication.