History and romance. In the past, amethyst from Russia was regarded as the ultimate gem. Described as a rich, deep purple with strong red secondary color, the Uralian or Siberian name now is used more as a color – rather than locality – designation, since little natural Russian amethyst is produced.
There is no shortage of localities for amethyst: Name almost any country and you’ll find some deposit of the purple quartz. However, the most important source is Brazil. Tons of material are mined there every year. Top gems of vivid saturation (but few red highlights) compare well to the old Russian stones. Bolivia, as well as other South American countries, also has notable deposits, but Bolivia is better known for having the only natural fine quality ametrine-a combination of amethyst and citrine in the same gem. (See “Enhancements” below.) Across the ocean in Zambia, amethyst of very fine quality with reddish color has been produced in the past few years. Even the United States has a respectable deposit of amethyst at Four Peaks, 7,200 ft. up in the Mazatzal mountain range just outside Phoenix. Four Peaks amethyst is one of the American gems leading the patriotic made-in-the-USA charge. (See “Purple Gems, Mountain Majesty,” JCK, July 1999, pp. l06-110.)
Colors. Most amethyst is a straight hue of purple, with varying degrees of tone and saturation. Everything from very light (almost colorless, as you might see on home shopping networks) to very dark, and from weak to vivid in saturations, is readily available. When tone and saturation are low, the gems tend to look somewhat pinkish. As mentioned above, the Russian material is best known for its reddish highlights. Siberian-quality color can be found in many locations but not in large amounts. Some material, as noted in gems from Four Peaks, also can be highlighted by violet, a bluish-purple, or a touch of brown, smoky quartz, resulting in red flashes.
Qualities. As expected with most transparent quartz, clarity can be literally flawless, especially in smaller stones of a few carats or less. In larger goods, 10 carats and up, expect to see some unimportant but possibly eye-visible inclusions, which may be a good thing (see “Synthetics” below). While the prominent color zoning from certain localities may decrease quality, it also can increase value because of its origin identification. The beauty of Four Peaks amethyst is two-fold: good color with positive identification features.
Enhancements and synthetics. Most amethyst is unenhanced, although some darker material is heated to lighten its color. In contrast, almost all citrine, the yellow-orange quartz, is heated amethyst. Only the commercially available citrine and ametrine from Bolivia is considered to be of natural color origin.
While Russia may no longer be the source for the best natural-color amethyst, it is the best source for the finest quality synthetic amethyst. So much synthetic amethyst is in the market today that close to 50% of all amethyst in retail jewelry stores might be synthetic-and the store owners probably don’t even know it. Since much of the synthetic material is free from identifiable inclusions, identification is a task for major gem laboratories with sophisticated equipment… and in most cases, the cost of identification is probably more expensive than the gem itself. Bulk testing in some laboratories has helped reduce the cost of amethyst identification.
Pricing. Because of the difficulty in identification, prices for small natural goods have merged with those for synthetics. Prices in The Guide for fine-quality I-ct. to 5-ct. stones range from $7 to $16 per carat. When there is positive natural identification, most likely in larger stones, prices can be elevated-to a point. Prices for fine-quality 10-ct. to 25-ct. amethyst range from $18 to $30 per carat. Over 25 cts., prices decrease, with prices for fine-quality goods ranging from $10 to $22 per carat.
Care and cleaning. Amethyst is durable and can be worn in all types of jewelry. However, as with all quartz (which has a hardness of 7), remember to wash off any dust before wiping the gem with a soft cloth. (Dust also has a hardness of 7 and can dull the surface of a polished gem.) Repolishing by a professional lapidary would be necessary to restore the luster of a dust-damaged gem.
Bench repair and setting. Amethyst is heat sensitive, so it is recommended that you remove or protect the stone from a jeweler’s torch.