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In its rough state tanzanite is coloured a reddish brown to clear, and it requires heat treatment to remove the brownish "veil" and bring out the blue violet of the stone. [7] The gemstone was given the name "tanzanite" by Tiffany & Co. after Tanzania, the country in which it was discovered. The scientific name of "blue-violet zoisite" was not ...
Nearly all tanzanite is heated at low temperatures to remove brown undertones and give a more desirable blue / purple color. [44] A considerable portion of all sapphire and ruby is treated with a variety of heat treatments to improve both color and clarity.
Ferric iron is the cause of the yellow in the stone. It has the misnomers olivine [2] and Uralian emerald. In approximately 2003, reports began to circulate in the trade that some Russian demantoid garnets were being routinely subjected to heat treatment in order to enhance their color.
Most amethyst will turn yellow or orange when heated, producing heat-treated amethysts which are often marketed as citrine, but some amethyst will turn green when treated. Currently, almost all prasiolite on the market is made from amethyst via a process of heating and irradiation. [5]
Heat treating furnace at 1,800 °F (980 °C) Heat treating (or heat treatment) is a group of industrial, thermal and metalworking processes used to alter the physical, and sometimes chemical, properties of a material. The most common application is metallurgical. Heat treatments are also used in the manufacture of many other materials, such as ...
Zoisite may be blue to violet, green, brown, pink, yellow, gray, or colorless. Blue crystals are known under the name tanzanite. It has a vitreous luster and a conchoidal to uneven fracture. When euhedral, zoisite crystals are striated parallel to the principal axis (c-axis). Also parallel to the principal axis is one direction of perfect cleavage.
Differential heat treatment is a method used to alter the properties of various parts of a steel object differently, producing areas that are harder or softer than others. This creates greater toughness in the parts of the object where it is needed, such as the tang or spine of a sword, but produces greater hardness at the edge or other areas ...
Gemstone irradiation is a process in which a gemstone is exposed to artificial radiation in order to enhance its optical properties.High levels of ionizing radiation can change the atomic structure of the gemstone's crystal lattice, which in turn alters the optical properties within it. [1]