Precious gemstone moonstone is a variety of orthoclase feldspar that shows a flash of white to blue-white color when viewed at the appropriate angle. It has perfect cleavage in one direction, good cleavage in another. It is coming from the class of framework silicates and has a monoclinic crystal system. The soft glow of this sheen resembles moonlight, so the stone is called precious gemstone moonstone with hardness level finish at 6 Mohs. The sheen itself is called schiller or adularescence, and is due to parallel layers of albite (sodium aluminium silicate) in the feldspar structure. The term adularescence is derived from the name adularia, which refers to colorless, transparent orthoclase (originally from Adular-Bergstock in Switzerland) that displays a bluish white sheen.
With specific gravity is ranging in 2.56-2.59 and a 0.012 dispersion, as a gemstone, precious gemstone moonstone is highly regarded for its beauty. It is composed from potassium aluminum silicate. Its habit is short prismatic or tabular crystals and also massive. Stones of a large size and fine quality are infrequent; however, precious gemstone moonstone is generally inexpensive. Certain varieties, particularly those that are larger and deeper blue, are highly prized by collectors. The highest quality and most sought-after precious gemstone moonstones come from Sri Lanka. Outher sources are Tanzania, Myanmar, Brazil, India, Madagascar, USA, and Switzerland. The best moonstone has a blue sheen and almost perfect clarity, and its body color is almost colorless. Precious gemstone moonstones can be faceted in a cushion cut, or, particularly when there is asterism or chatoyancy, cut en cabochon. Cameos are also popular.
Orthoclase is found as a rock-forming mineral in igneous, plutonic, and metamorphic rocks, but rarely as precious gemstone moonstone. The refractive index is in between 1.520-1.525 and its birefringence 0.005. Adularia is found in low-temperature hydrothermal deposits. Precious gemstone moonstone as extravaganza natural gemstone comes in a variety of colors and shades, but is most often a whitish blue. Colors available are colorless to gray, white to blue sheen, brown, pink, green, and yellow. Precious gemstone moonstone has vitreous luster and uneven fracture.
Characteristic microscopic inclusions look like small caterpillars in the gem. Polished precious gemstone moonstones from Burma (Myanmar) sometimes exhibit chatoyancy (a narrow band of reflected light that produces a cat’s eye effect). A variety with multicolored sheen, known as rainbow precious gemstone moonstone, is related calcium-rich plagioclase feldspar.
