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This is a list of gemstones, organized by species and types. Minerals ... Rock crystal (var.) Shocked quartz (var.) Smoky quartz (var.) Quartzite; R–Z. Realgar;
Many gems are crystals which are classified by their crystal system such as cubic or trigonal or monoclinic. Another term used is habit, the form the gem is usually found in. [12] For example, diamonds, which have a cubic crystal system, are often found as octahedrons. [13] Gemstones are classified into different groups, species, and varieties.
Bahia Emerald [2]; Carolina Emperor, [3] [4] 310 carats uncut, 64.8 carats cut; discovered in the United States in 2009, resides in the North Carolina Museum of Natural Sciences, Raleigh, NC, US
^ Florida's state gem, moonstone, was adopted to highlight Florida's role in the United States' Lunar program, which landed the first astronauts on the Moon. [81] ^ Since 1983, Massachusetts has had 3 other official state rocks: State Historical Rock (Plymouth Rock), State Explorer Rock (Dighton Rock), and State Building and Monument Stone . In ...
Asterism is generated by reflections of light from twin-lamellae or from extremely fine needle-shaped acicular inclusions within the stone's crystal structure. [1] A common cause is oriented sub-microscopic crystals of rutile within the gem mineral. It occurs in rubies, sapphires, garnet, diopside, and spinel when a cabochon is cut from a ...
Gemstones are basically categorized based on their crystal structure, specific gravity, refractive index, and other optical properties, such as pleochroism. The physical property of "hardness" is defined by the irregular Mohs scale of mineral hardness. Gemologists study these factors while valuing or appraising cut and polished gemstones.
A few gem-grade sapphires and rubies have also been found in the area of Franklin, North Carolina. [35] The sapphire deposits of Kashmir are well known in the gem industry, although their peak production took place in a relatively short period at the end of the nineteenth and early twentieth centuries.
A crystal or crystalline solid is a solid material whose constituents ... such as oxides like aluminium oxide found in many gemstones such as ruby and synthetic sapphire.