While the Ural Mountains are now inactive, they produced some of the finest amethyst known to the extent that any top color amethyst gemstone, regardless of origin, is referred to as Uralian amethyst.
Of modern sources, it is the gemstones from South African that set the standard for excellence: Namibia, Zambia and Tanzania. This broad area is known as the Umba Valley, a veritable treasure trove of some of the world's finest colored gemstones. South American countries provide the bulk of commercial quality amethyst. Gemstones form Argentina, Bolivia, Brazil and Uruguay account for most of the world's supply. Amethyst can also be found in Mexico, Western Australia, Sri Lanka and Madagascar, and in several states in the US including Maine, New Hampshire, North Carolina, Virginia, Georgia and Montana.
Photo: Amethyst Ring Custom Design and Handmade by Tom Owczarzak
It's generally true for almost all colored stones that that best specimens are packed with color, "saturated." However, in grading a colored gemstone there are other factors that are equally important: brilliance and clarity. For amethyst, well, for any colored gemstone, a specimen that is so dark it's difficult to discern the actual color is a very poor quality gem and has little value. Amethyst owes it's color to manganese impurities. Another variety of quartz, citrine, can be heated to turn purple and is then sold as amethyst. Imitation amethyst is almost always uniformly colored while natural amethyst will show some color banding referred to as "zebra stripes." Amethyst gems from Africa tend to be smaller in size, a deep royal purple and have flashes of red. Amethyst gems from South American countries can generally be much larger and have a softer purple with flashes of blue.
Photo: Custom Design Handmade Natural Amethyst Earrings by Lisa Voelker, All Animal Jewelry