12 Diamond Coated Dormer Drill Bits Great for Metalsmiths, Metal Working & Drilling. This is a new set of 12 diamond coated twist drill bits. Made with electroplated diamond particles great for drilling stone, ceramic, glass, and other hard non-metallic materials. These are made of superior high grade steel. All drill bits are medium to fine grit. Use with standard handpiece and a small amount of water as lubricant. These have 3/32" (2.3 mm) shanks. These bits measure approximately 0.889, 0.99, 1.181, 1.397, 1.512, 1.613, 1.702, 1.778, 1.994, 2.083 and 2.705 mm (0.034", 0.038", 0.046", 0.054", 0.059", 0.063", 0.067", 0.069", 0.078", 0.082" and 0.106").