1/8" Inch 3.3 mm DiamondSure Diamond Drill Bit Holes Saw for Glass, Tile, Granite, Ceramic, Porcelain, Stone,DiamondSure,900-001" /> Electroplate bonded diamonds for optimum diamond life for drilling to depths of about 1/2". Nickel Plated: Reduces bit friction and heat build-up and inhibits rust. Tip Lubrication Hole: Provides optimum tip lubrication by allowing water flow in and out of bit. Core Extraction Hole: Special holes in back of the "Bell" allow easy removal of cores or plugs. Not designed for use on concrete, masonry, metal or for use with impact hammer drills.