6 Diamond Coated Twist Drill Bits Great for Metalsmiths, Metal Working & Drilling. This is a new set of 6 diamond coated twist drill bits. Made with electroplated diamond particles great for drilling stones, pearls, glass or ceramics. 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 0.038, 0.042, 0.053, 0.060, 0.067 and 0.075 mm (0.0014", 0.0016", 0.002", 0.0023", 0.0026" and 0.0029").