Industrial diamond drill used as a grinding & polishing agent. The cutting edge of the tool is the small diameter end, encrusted with diamonds, which have been electroplated into the tip. It is driven around like a drill, with high pressure water pumped through the middle to keep the temperature down & flush away debris. Industrial diamonds are generally from the variety of diamond known as bort. These are colourless, twinned, fissured, cracked or otherwise flawed diamonds, i.e. not suitable for gems.