Quartz crystals and other gems do not begin their lives as pristine, lovely rocks, but as scarred, oddly shaped stones called rough. They may have chips or undesirable sections that need to be removed, and often bare little resemblance to their final shape. To begin with, the quartz crystals are cut with a coarse, rotating disk, which functions as a saw. This saw spins at a high rate of speed, and the quartz crystal is slowly pushed down against it, carving it in two. As the saw spins, water or oil is shot into the junction where it meets the quartz. This water washes away debris and keeps the saw from overheating. A lapidary or gem cutter will use the saw to cut the quartz into the approximate shape he desires.
Grinding, Sanding and Lapping
The quartz crystal is then polished by grinding and sanding. The grinding wheel is dotted with very coarse bumps made out of an extremely hard material such as silicon carbide. It spins rapidly and is pushed against the quartz to slowly wear it away into a chosen shape. Once the gem cutter creates a rough shape by grinding, he uses a finer-grained wheel to sand the quartz. Sanding removes the scrapes left by grinding, smoothing the crystal. Sometimes, gem cutters use a process called lapping, which uses a spinning or agitating disk instead of a rotating wheel. Lapping works in much the same way as grinding and sanding, but is used specifically to make flat surfaces.
Polishing is what gives finished quartz crystals their bright, flawless surface. Depending on the particular stone, different materials can be used for polishing. The stone could be polished with a very fine sanding wheel with extremely tiny grains, or it might be rubbed with wood, leather or some other fairly soft material. The polishing process wears away tiny imperfections in the surface of the crystal, making it appear more beautiful and luminous.