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Some tourmaline gems, especially pink to red colored stones, are altered by heat treatment to improve their color. Overly dark red stones can be lightened by careful heat treatment. The pink color in manganese-containing near-colorless to pale pink stones can be greatly increased by irradiation with gamma-rays or electron beams.
As a gemstone, elbaite is a desirable member of the tourmaline group because of the variety and depth of its colours and quality of the crystals. Originally discovered on the island of Elba , Italy in 1913, it has since been found in many parts of the world.
Rubellite is the red or pink variety of tourmaline and is a member of elbaite. Rubellite is also the rarest gem in its family. [2] It is occasionally mistaken for ruby. [3] These gems typically contain inclusions. [4] Notable countries where rubellite can be mined include Afghanistan, Brazil, Madagascar, Myanmar, Nigeria, Russia, and the United ...
Amethyst crystals – a purple quartz Apophyllite crystals sitting right beside a cluster of peachy bowtie stilbite Aquamarine variety of beryl with tourmaline on orthoclase Arsenopyrite from Hidalgo del Parral, Chihuahua, Mexico Aurichalcite needles spraying out within a protected pocket lined by bladed calcite crystals Austinite from the Ojuela Mine, Mapimí, Durango, Mexico Ametrine ...
Pleochroism is an extremely useful tool in mineralogy and gemology for mineral and gem identification, since the number of colors visible from different angles can identify the possible crystalline structure of a gemstone or mineral and therefore help to classify it. Minerals that are otherwise very similar often have very different pleochroic ...
The "chelsea" filter was originally devised by Anderson and Payne in 1934 of the Gem testing Laboratory of the London Chamber of Commerce & Industry.The filter was devised with the collaboration of gemmology students of the Chelsea College of Science and Technology where Basil Anderson was an instructor for the Gemmological Association of Great Britain.
Mineral details specifying species of tourmaline etc, and then a seperate section dealing with the gem varieties (that are typically based on color - ignoring the mineral species), rubellite, indicolite, paraiba, bicolor, etc. BTW I would like to confirm whether the statement made by Krementz that "almost all the jewelry-usable material is ...
Peridot, a gem-quality olivine; Archaically, any of several green or yellow-green-coloured gemstones including Topaz, a silicate mineral of aluminium and fluorine; Chrysoberyl, an aluminate of beryllium; Zircon, a mineral belonging to the group of nesosilicates; Prehnite, an inosilicate of calcium and aluminium