... /Top: Round, Trigonal, Hex (3). Diamond grit: D427, D252, D181 and cutting thickness upon coating grit (4). Custom steel cores available ... to drill marble, ceramics, porcelain, tile, glass, fiberglass, quartz, bricks, and a variety of other materials. (7). It gives excellent clean ... as exceptionally long life. (8). It is very easy to assemble and use with or without center pin. Drill: Step Drill Core ...