Diamond Drill Bits and countersinks are diamond tools for glass hole drilling and countering. They can also drill holes like ceramic, porcelain, stone, limestone, gemstones, marble, granite, slate, shell and bone. As well as agate drilling or core extraction. Diamond Drill Bits include different shank types, such as straight shank, taper shank, internal and external threaded shank. Diamond-section wall thickness usually 1mm and height 10mm around.