In the flame-fusion process—invented in 1904 by the French chemist Verneuil—powdered aluminum oxide, containing coloring agents, is sieved down through the flame of a vertical blowtorch furnace. As it passes through the flame, the powder melts and accumulates as drops on an adjustable stand just below the flame, where it forms a single crystal _boule_ of the synthetic rough. In a few hours a boule of several hundred carats can be formed. When such furnaces are operated in banks of several hundred units, the commercial production of corundum alone becomes possible at the rate of many tons a year. Through the years, of course, refinements have been made on Verneuil’s original furnace. In the hydrothermal process, which differs greatly from Verneuil’s flame-fusion process, crystals are grown from solutions of the raw materials that have been subjected to varying conditions of very high pressure and temperature. Some of the quartz used for electronics purposes also is manufactured in this way. Since chemical composition and crystal structure are the basic characteristics by which a gemstone is identified, and these characteristics are identical in both the manufactured stone and its natural counterpart, the synthetic gemstones offer a very serious challenge to those concerned with gem identification. 5 GEM LORE All sorts of magic and symbolic properties have been ascribed to gemstones through the ages; for example, the cat’s-eye has been prescribed as a cure for paleness, citrine has been worn as a protection from danger, and the opal cherished as the symbol of hope. The result has been the creation of an intricate, chaotic, and contradictory but interesting mass of gem lore. Among the treasures in the Smithsonian’s Museum of Natural History is a very old silver breastplate that once was in an ancient synagogue and supposedly was modeled after the one worn by Aaron, the first high priest of the Hebrews. In this plate are mounted twelve stones representing the Twelve Tribes of Israel. Among Christians, the Twelve Apostles also were represented symbolically by precious stones. THE TWELVE TRIBES Levi, _Garnet_ Zebulon, _Diamond_ Gad, _Amethyst_ Benjamin, _Jasper_ Simeon, _Chrysolite_ Issachar, _Sapphire_ Naphtali, _Agate_ Joseph, _Onyx_ Reuben, _Sard_ Judah, _Emerald_ Dan, _Topaz_ Asher, _Beryl_ THE TWELVE APOSTLES Peter, _Jasper_ Andrew, _Sapphire_ James, _Chalcedony_ John, _Emerald_ Philip, _Sardonyx_ Bartholomew, _Sard_ Matthew, _Chrysolite_ Thomas, _Beryl_ James the Less, _Topaz_ Jude, _Chrysoprase_ Simon, _Hyacinth_ Judas, _Amethyst_