Any rough mineral or other material natural or synthetic, which possesses the necessary attractiveness, brilliance, beauty, rarity, color dispersion, refraction, color or colorless, flawless, portability, fashionably, and durability for use in gem industry. For identification gems are superficially examined by color, optic qualities, sight, and coolness, but require some scientific examination such as determination of specific gravity, hardness, refractive index, crystal system (when crystallized), dichroism, absorption spectra, etc. All minerals, as well as the opal are gemstones, but all type of glass and plastics are excluded.
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