Gemstone Chart |
Natural Sillimanite Sillimanite is an alumino-silicate mineral with the chemical formula Al2SiO5. Sillimanite is a very rare trimorph and it has a common variety called fibrolite. Color: violet blue, grey green, colorless, brown, green, Categories: semi-precious stone Chemical Composition: Al2OSiO4 Crystal Group: Orthorhombic Refractive Index: 1.658 - 1.678 Hardness: 6 - 7.5 Density: 3.25 Occurrence: France, Madagascar, U.S.A., Sri Lanka, Burma. Kenya
| Natural Spinel Spinel is the magnesium aluminium member of the larger spinel group of minerals. It has the formula MgAl2O4.Pure spinel is white, but impurities give it a wide range of colors.Almost all colors are used in jewelry, but the most valuable and popular color is the deep red. Spinel is cut into gems for use as jewelry. The deep-red variety, known as ruby spinel, is the most prized form. Color: orange, pink, black, blue, lavender, mauve, greenish blue, and vivid red Categories: semi-precious stone Chemical Composition: MgAl2O4 Crystal Group: Cubic Refractive Index: 1.718 (-.006,+.044) Hardness: 8 Density: 3.60 (-.03, +.30) Occurrence: Mogok, Burma; Sri Lanka; Amboseli district, Kenya; Jemaa district, Nigeria; Matombo, Umba, and Tunduru Tanzania; Hunza, Pakistan; Pamir range, Tajikstan; Luc Yen, Vietnam; Madagascar; Australia; Sweden; Brazil.
| Natural Star Sapphire A star sapphire is a lovely gem that exhibits a six pointed star because of the intersection of six thin intersecting inclusions. When the gem is lit from above, the inclusions become quite visible and the star shape appears.A powdery grey-blue star sapphire is the centerpiece of a ring from the Art Deco period. Color: Blue, green blue, violet, blue, black, brown, pink. Categories: semi-precious stone Chemical Composition: AL2O3 Crystal Group: Hexagonal Refractive Index: 1.759-1.778 Hardness: 9 Density: 4 Occurrence: Sri Lanka, Burma, India, East Africa, Ankarana-Madagascar, Thailand.
| Natural Zircon Zircon is a mineral belonging to the group of nesosilicates. It is one of the heaviest gemstones, which means that it will look smaller than other varieties of the same weight. Zircon occurs in a wide range of colours,the most popular colour is blue zircon. The wide variety of colours of zircon, its rarity, and its relatively low cost make it a popular collector's stone. Color: Brown, blue, red, orange, white, green Categories: semi-precious stone Chemical Composition: ZrSiO4 Crystal Group: Tetragonal Refractive Index: 1.780-1.984 Hardness: 7.5 Density: 4.00-4.73 Occurrence: Ceylon, Burma,France, Norway, East Africa,Australia, SE Asia.
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