| Gemstone Chart |
 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.
|  Natural Chrome Tourmaline
Chrome tourmaline is a beautiful bottle-green variety of the gemstone. Gem-quality chrome tourmaline is quite pricey and is found in East Africa.
Color: dark green, light green, yellowish green
Categories: semi-precious stone
Chemical Composition: (NaCa)(LI,MgFe,Al)9B3Si6(O,OH)31
Crystal Group: Hexagonal
Refractive Index: 1.624(+.005, -.005) - 1.644(+.006, -.006)
Hardness: 7-7.5
Density: 3.06 (.05, +.15)
Occurrence: East Africa
|  Natural Chrysoberyl
The Chrysoberyl family is best known for the more valuable alexandrite and catseye varieties. Faceted chrysoberyl is a beautiful gem which is not as well known in its own right. Apart from the high hardness, it takes a good polish and has a good luster.
Color: yellow, green, color changing, red, blue-green, greenish-yellow or brown
Categories: semi-precious stone
Chemical Composition: BeAl2O4
Crystal Group: Orthorhombic
Refractive Index: 1.741 - 1.760
Hardness: 8.5
Density: 3.73
Occurrence: Ceylon, Tanzania, Russia, Madagascar, Brazil.
|  Natural Chrysoberyl Cats Eye
Chrysoberyl cats eye is a very rare and expensive gemstone which is found in small quantities in Sri-Lanka and Brazil. The cats eye is present because the stone has chatoyancy in its make up and this effect cause the ¡®eye¡¯ which moves as the gem is gently turned .
Color: yellow, greenish yellow, yellowish green
Categories: semi-precious stone
Chemical Composition: BeAl2O4
Crystal Group: Orthorhombic
Refractive Index: 1.741 - 1.760
Hardness: 8.5
Density: 3.73
Occurrence: Ceylon, Tanzania, Russia, Madagascar, Brazil.
|  Natural Chrysocolla Quartz
Chrysocolla quartz is chalcedony mixed with varying amounts of chrysocolla. The chrysocolla provides the robin's egg blue coloration, and the quartz provides sufficient hardness for use in jewelry.
Color: green, blue, white
Categories: semi-precious stone
Chemical Composition: SiO2
Crystal Group: Hexagonal
Refractive Index: 1.544 - 1.553
Hardness: 7
Density: 2.66
Occurrence: Arizona, Mexico
|  Natural Chrysoprase
Chrysoprase is a gemstone variety of chalcedony or cryptocrystalline quartz, colored by trace amounts of nickel.
Categories: semi-precious stone
Chemical Composition: SIO2
Crystal Group: Hexagonal
Refractive Index: 1.544 - 1.553
Hardness: 7
Density: 2.65 - 2.66
Occurrence: Australia, Tanzania
|  Natural Citrine
Citrine is any quartz crystal or cluster that is yellow or orange in color. Although often cut as a gemstone, citrine is actually somewhat rare in nature.
Color: Yellow, orange
Categories: semi-precious stone
Chemical Composition: SiO2
Crystal Group: Trigonal
Refractive Index: 1.544-1.553
Hardness: 7
Occurrence: Brazil, Uruguay, Mexico, Russia, USA.
|  Natural Clinohumite
Clinohumite is a rare mineral and an especially rare gemstone. It is a member of the humite group of minerals, which includes humite, clinohumite, chondrodite, and norbergite.Only two sources of gem-quality material are known: the Pamir Mountains of Tajikistan, and the Taymyr region of northern Siberia.
Color: Brown, yellow, white, orange, or reddish brown
Categories: semi-precious stone
Chemical Composition: Magnesium Silicate Fluoride OH
Crystal Group: Monoclinic
Refractive Index: 1.625 ¨C 1.668
Hardness: 6 - 6.5
Density: 3.17 - 3.35
Occurrence: Extremely rare - gem quality found only in the Pamir Mountains, Tadzhikistan. Other mineralogical occurrences include, Mt. Vesuvius, Italy; Pargas, Finland; Llanos de Juanar, Malaga, Spain; Tilly Foster Mine, New York; Fort Defiance, Apache County, Arizona; Crestmore Quarry, Riverside County and Lower Lake, Fresno County, California; Luna, New Mexico and Franklin, New Jersey, USA.
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