20 Diamond Burs Lapidary Rock Grinding Tool This is a new set of 20 diamond coated burs These are 150 grit They can be used with a Dremel tool This master diamond bur set allows you to shape, grind and finish with precision Great for filing glass, ceramics, tile, brick, plastics, wood, fiberglass, stone, rock carbide, gold, platinum, silver, metals or anything else that is hard