Tyndall scattering is one of the rarest phenomena in gemology, but it is relatively common in Madagascar rose quartz. ![]() Indeed, one of its best uses is for star cabs and spheres. Until the 1980s, when a new deposit was discovered in Madagascar, it was never found completely transparent. It is always a light to medium pink, but sometimes is influenced by amethyst and picks up a violet shade. Rose quartz receives its coloring fromfibrous inclusions of a mineral similar to dumortierite. The person who wants a really big gem, without a really big budget, often ends up with one of these. Smoky quartz is known for its large sizes. "Chocolate citrine" is a pleasant brownish/yellow color. It comes in every shade of brown, from a light tan to nearly black. However, a well cut, bi-colored gem is a real delight. Cutting the material so both color show is sometimes a challenge for the lapidary. The colors only reach a medium level of saturation and are never very dark. Relatively new on the market is ametrine, with zones of both purple and yellow. It is created by heat treating citrine with the proper iron content and demands the highest price. "Madeira" citrine is a strong orange color, with red flashes. Its color ranges from a light lemon yellow, to a rich orange. These are the colors traditionally associated with topaz, and they are still confused by many. CitrineĬitrine is the yellow to orange variety of quartz. Today, the variety most in demand is "Siberian." That does not refer to its origin, but to dark purple coloring, with flashes of red or blue. The lightest shades are called "Rose de France." While currently out of vogue, they have traditionally been very fashionable. AmethystĪmethyst ranges from a light, pinkish violet to an opaque purple. However, it is prized by carvers and frequently used as caps for triplets. Rock crystal, colorless quartz, is rarely used as a gem. There are many other natural varieties, plus synthetic quartz that comes in every color of the rainbow. (See The X Factor.) It is well loved as amethyst, citrine, rose, and smoky quartz. ![]() Quartz is one of the most common minerals on earth. Quartz is common, except Dumortierite quartz which is somewhat rare. The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
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