Gemcutting facts

   Gemcutting is the cutting and pol­ishing of precious stones in order to reveal their full beauty. In their natural state gems are usually dull lumps of rock. Until the 14th century they were mostly cut round or oval and polished without facets (flat surfaces). Opals, moonstones, and a few others are still cut in this way, but most of the transparent gems are cut in facets. Faceting causes the gem to reflect pinpoints of light from all its surfaces and gives the stone the brilliance that we admire.
   The main centers of the gemcutting industry are Antwerp, Belgium; Idar-Oberstein, Germany; and Amsterdam, The Netherlands. During World War II many European gemcutters went to England and the United States and established the industry in those countries.
   Diamonds are cut into rough shapes on a saw, consisting of a met­al disk, the edge of which is set with diamond dust. Since a diamond is the hardest of all minerals, it can be cut only with diamond. For other gems the wheel is usually made of Carborundum. To cut it to its final shape the gem is fastened with a strong cement on the end of a wood-en stick, called a lap or dop stick. The stone is then held against a revolving stone grinding wheel to grind the facets. The wheel is usually cooled by a small stream of water. For polishing the gem the wheel is covered with felt on which fine abrasive powder is rubbed. The finished gem is then ready to be set in a piece of jewelry.