Tanzanite Vodka in Gift Box - 70cl Premium French Vodka

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Tanzanite". Gemstone.org. Archived from the original on 12 September 2008 . Retrieved 29 August 2011. Study of Heat Treatment". Yourgemologist.com. International School of Gemology . Retrieved 29 August 2011. There is no universally accepted method of grading colored gemstones. TanzaniteOne, a major commercial player in the tanzanite market, through its non-profit subsidiary, the Tanzanite Foundation, [27] has introduced its own color-grading system. [28] The new system's color-grading scales divide tanzanite colors into a range of hues, between bluish-violet, indigo and violetish-blue. In June 2003, the Tanzanian government introduced legislation banning the export of unprocessed tanzanite to India. (Like many gemstones, most tanzanite is cut in Jaipur.) The reason for the ban is to attempt to spur development of local processing facilities, thereby boosting the economy and recouping profits. This ban was phased in over a two-year period, until which time only stones over 0.5 grams were affected. [ citation needed] In 2010, the government of Tanzania banned the export of rough stones weighing more than one gram. [19]

Tanzanite may be subjected to other forms of treatment as well. Recently, coated tanzanites were discovered and tested by the AGTA and AGL laboratories. [34] A thin layer containing cobalt, determined by X-ray fluorescence, had been applied to improve the color. It was noted that "coatings in particular are not considered permanent", and in the United States are required to be disclosed at the point of sale. Tanzanite forms as a brownish crystal and is trichroic, which means it shows three colors – brown, blue and violet – concurrently. Heating, either underground naturally by metamorphic processes, or artificially, removes the brown or burgundy color component to produce a stronger violet-blue color and makes the stone "dichroic", which means it only reflects blue and violet. [30] Rarely, gem-quality tanzanite will heat to a green primary hue, almost always accompanied by a blue or violet secondary hue. These green tanzanite have some meaningful value in the collector market, but are seldom of interest to commercial buyers. [31] The normal primary and secondary hues in tanzanite are blue and violet. Untreated tanzanite is a trichroic gemstone, meaning that light that enters this anisotropic crystal gets refracted on different paths, with different color absorption on each of the three optical axes. As a result of this phenomenon, a multitude of colors have been observed in various specimens: shades of purple, violet, indigo, blue, cyan, green, yellow, orange, red and brown. After heating, tanzanite becomes dichroic. The dichroic colors range from violet through bluish-violet to indigo and violetish-blue to blue. [29] Eugenia Sheppard (3 October 1968). Section B. "Inside Fashion: Something new at Tiffany's is Tanzanian blue gem". Durham Morning Herald (finaled.). Durham, N.C.: The Durham Herald Co.: 2B. OCLC 9519676.

There are many accounts of the discovery of tanzanite, but only one recognised by the government of Tanzania. In January 1967, Jumanne Mhero Ngoma (originally from Same District, Kilimanjaro) stumbled upon the sparkling blue stones at the Mererani hills in the Kiteto district of the then Arusha Region (presently Manyara Region). He was issued with a certificate of recognition three years later by the then President Julius Nyerere and a financial reward of Tsh 50,000 for his efforts. In 1984, he was issued with a certificate for scientific discovery by the Tanzania Commission for Science and Technology. [10] [11] Commercial history [ edit ] Craft work on tanzanite

verifyErrors }}{{ message }}{{ /verifyErrors }}{{ E. Skalwold. "Pleochroism: trichroism and dichroism in gems". Nordskip.com. Archived from the original on 6 September 2012 . Retrieved 29 August 2011. Tanzanite was formed around 585 million years ago during the mid- Ediacaran Period by massive plate tectonic activity and intense heat in the area that would later become Mount Kilimanjaro. The mineral is located in a relatively complex geological environment. Deposits are typically found in the "hinge" of isoclinal folds. [9] Discovery [ edit ] Featured gemstone: tanzanite". GIA Library. Gemological Institute of America, Inc. Archived from the original on 13 May 2008.As of 2020 [update], tanzanite has never been successfully synthesized in a laboratory, so all genuine tanzanite is naturally occurring. However, because of its rarity and market demand, tanzanite has been imitated in several ways. Among the materials used for this are cubic zirconia, synthetic spinel, yttrium aluminium garnet, and colored glass. A test of the stone with a dichroscope can easily distinguish these from genuine tanzanite, as only tanzanite will appear doubly refractive: the two viewing windows of the dichroscope will display different colors (one window blue, the other violet) when viewing genuine tanzanite, while the imitation stones are all singly refractive and will cause both windows to appear the same color (violet). [36] The Tanzanite Foundation". The Tanzanite Foundation. 22 April 2013. Archived from the original on 9 February 2005 . Retrieved 26 November 2013.

From 1967, an estimated two million carats of tanzanite were mined in Tanzania before the mines were nationalized by the Tanzanian government in 1971. Mgunduzi wa madini Tanzanite afariki dunia". BBC News Swahili (in Swahili) . Retrieved 26 September 2023.

The physical characters can make cutting process difficult due to the problem of selecting the perfect color. The finished color of the gemstone will vary depending on how the table cut reflects the light. [35] Imitation and cobalt-coated tanzanite [ edit ]

Coatings: a new Tanzanite treatment uncovered". farlang.com. Farlang's Gem and Diamond Foundation; Gemological Association of Great Britain; German Gemological Association; Netherlands Gemological Laboratory. 25 May 2008. Muchira, John (24 May 2013). "TanzaniteOne cedes 50% stake to State as new law takes effect". Mining Weekly. Since heat treatment is universal, it has no effect on price, and finished gems are assumed to be heat-treated. Gemological Institute of America states that the source of heating is gemologically undetectable, but is assumed because of its prevalence. [33]National Environment Statistics Report - Tanzania Mainland" (PDF). National Bureau of Statistics (NBS) (Tanzania). June 2018 . Retrieved 27 June 2020. Briggs, Philip; McIntyre, Chris (2013). Tanzania Safari Guide: With Kilimanjaro, Zanzibar and the Coast. Bradt Travel Guides. p.104. ISBN 978-1-84162-462-4.