... drilling performance: High speed,Smooth cut. Electro-plated diamond core drill bit (hole saw) :-Fast, clean and efficient ... (2). Shank/Top: Round, Trigonal, Hex (3). Diamond grit: D427, D252, D181 and cutting thickness upon coating ... (6). Used to drill marble, ceramics, porcelain, tile, glass, fiberglass, quartz, bricks, and a variety ... or without center pin. Electroplated diamond tile drill bit