| Gemstone Chart |
 Natural Amethyst
As a member of the quartz family, amethyst is one of the most common, hence under-appreciated, gemstones on the market.
Color: purple, violet
Categories: semi-precious stone
Chemical Composition: SiO2
Crystal Group: Hexagonal
Refractive Index: 1.544 - 1.553
Hardness: 7
Density: 2.66
Occurrence: Brazil, Uraguay, Bolivia, Madagascar, Russia, USA, Zambia
|  Natural Chalcedony
Chalcedony is a catch all term that includes many well known varieties of cryptocrystalline quartz gemstones. They are found in all 50 States, in many colors and color combinations, and in sedimentary, igneous, and metamorphic rocks.
Color: grayish, purple, white, green, blue, lavender, yellow, brown
Categories: semi-precious stone
Chemical Composition: SiO2
Crystal Group: Hexagonal
Refractive Index: 1.530 - 1.539
Hardness: 6.5
Density: 2.57 ¨C 2.64
Occurrence: Brazil, U.S.A. Germany, India, Uruguay, Austarlia, Egypt, Italy, Scotland, South Africa, Namibia, Madagascar, Mexico, Tanzania, and many other localities throughout the world.
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