The wide range of topaz colors available are due either to natural trace impurities or crystal structural defects. Diversity in color is also caused by changes produced by the gemstone industry. Topaz is available in a variety of colors from yellow, orange, gray, purple, blue, black, violet and green. Colorless topaz is fairly common and is rarely given a dazzling cut and sold as a diamond replacement.
The most common colors of untreated topaz are pale yellow, brown and gray. Pastel shades of light-green, violet and pink are also found.
The most popular topaz color is blue. Indeed, blue topaz is the perennial top selling jewelry stone in the USA. The most valuable topaz colour known as imperial topaz, is an orange to pink colour. The exact color is not well known for imperial topaz, so a wide range of golden orange, peach and pink topaz are offered under this name. Several light-pink topaz gems are the result of treatment with heat. Imperial Topaz, also known as Precious Topaz is the rarest and most valuable of the Topaz family, coming in colors ranging from golden yellow to the extremely prized sherry pink color.
Tpoaz which is aluminum flurosilicate is normally colorless in the absence of impurities. Mystic Topaz The bright pink colour is also created using a special high tech process which is called thin-film deposition. Was this article helpful? Related Articles. Morganite is set to shine as Pantone release the color of the year 1st Nov In you won t see just one color taking How Does Alexandrite Change Color?
Latest Articles. Approved Gemstone Testing Laboratories 10th Nov Gem rock auctions has one of the largest range of Green Gemstones: Which Gems are Green? Search the Gemstone Encyclopedia Search Encyclopedia. You can read the rest by visiting the NRC website. These valley fills were once thought to be deposited by water, but now many of them are believed to have been deposited by ground surges of hot ash.
The Topaz Mountain Rhyolite has many vuggy areas, which often contain champagne-colored topaz crystals. USGS image. Placer Topaz: Topaz has a high specific gravity, and because of that it is commonly concentrated by stream currents into placer deposits.
Much topaz has been produced from placer deposits in Brazil and Nigeria. The topaz pebbles in the photo above are from Brazil and were rounded and frosted during stream transport. The fluorine in its composition is a limiting factor on its formation.
Fluorine gas in concentrations high enough to form minerals only occurs in a few geologic environments. Most topaz grows as crystals within the veins and voids of igneous rocks. This topaz is found in the cavities of a pegmatite , or in the vesicles and intergranular spaces of rhyolite. These topaz crystals grow during the late stages of magma cooling and while degassing releases the fluorine necessary for topaz crystal growth. Precipitating in cavities, topaz sometimes develops nicely formed crystals.
These crystals can have excellent clarity and can be used as a gem material. Many mineral collectors enjoy collecting gem-quality topaz crystals because they have the value of an excellent mineral specimen plus if they are of rare color the value of a gem material. Topaz is also found as water-worn pebbles in stream sediments derived from the weathering of pegmatites and rhyolites. These are often produced by placer mining. Topaz is found in many locations worldwide where rocks like pegmatite and rhyolite are formed.
Here, topaz is usually a minor mineral in terms of quantity, and a secondary mineral in terms of its time of formation. Brazil has been the world's most important source of topaz for decades.
Almost all of the world's fine-quality imperial topaz is produced in the state of Minas Gerais in southeastern Brazil. The Ouro Preto and Capao mines have been the most important sources of yellow, orange, pink, red and violet topaz crystals for the gem and mineral specimen markets. Brazil is also the leading producer of colorless topaz, much of which is heat treated and irradiated to produce the colors of Swiss blue and London blue.
Pakistan is a smaller but noteworthy source of pink, red and violet topaz. Sri Lanka is a very important source of colorless topaz. In the United States, some topaz is produced in Utah , where it was named the state gemstone in The name "topaz" has often been used incorrectly or inappropriately in conversation and commerce. These incorrect uses of a name are called "misnomers". Misnomers can be used in three ways:. The word topaz is used in all of the above ways and perhaps more. A list of topaz misnomers is provided below with a brief description for each misnomer.
Many of them are archaic, but they can still be encountered in writings and discussions. Professionals in the gem and jewelry industry should avoid the use of these terms and use proper mineral species and variety names. It is especially used when these materials are produced by heat treating amethyst. The Federal Trade Commission, in their new edition of Guides for the Jewelry, Precious Metals, and Pewter Industries, clearly indicates that using incorrect varietal names can be misleading and deceptive.
Incorrect varietal names are misnomers. A vendor who uses them as product names, or in product promotion, descriptions, labels, etc. For that reason, it is best to avoid misnomers completely. The Federal Trade Commission used the names "green amethyst" and "yellow emerald" as examples of names that are problematic. Home » Gemstones » Topaz Topaz A gemstone that occurs in a wide range of natural and treated colors.
Author: Hobart M. Color Natural colors include: colorless, yellow, orange, brown, red, pink, blue, green. The steelmaking industry uses most of the refractory materials produced. Topaz can also be used as a raw material in the production of fluorine compounds, and in ceramic and glass manufacture. The name topaz has been used for any yellowish gemstones for at least two thousand years.
Gem traders did not know that these yellowish stones were actually different minerals until about two hundred years ago. Gem traders recognised that quartz, beryl, corundum and olivine all had yellow variants and were not true topaz and that topaz could be other colours not just yellow. In addition, the island Topazios, after which the gemstone has been named, never produced topaz, but was a source of peridot, or olivine often confused as topaz.
The island is now called Zabargad Island. Ancient Egyptians believed that yellow topaz received its golden colour from the Sun God, Ra.
The ancient Greeks believed that topaz gave them strength and topaz is mentioned in the modern translation of the bible, although the word probably referred to a yellow stone, not necessarily true topaz. During the middle ages, the main source of topaz was from a deposit in the Erzgebirge Mountains in Germany. Hundreds of kilograms of yellow to brown topaz crystals were mined from the deposit. Then in the s, a large topaz deposit was discovered in the Minas Gerais region of Brazil.
During this period, Brazil was a colony of Portugal, so in , the Portugese Government officially recognised the deposit as an important commercial mine, and most of the gems were transported back to Europe. Brazil remains the largest producer of Topaz in the world. Gem quality topaz was first found in Australia as a by-product of metal mining operations. In , tin was discovered in the New England area of New South Wales and mining commenced shortly afterwards.
When the miners concentrated the alluvial material, sometimes they found pebbles of topaz. Waterworn topaz was found associated with gold, tin and wolfram deposits throughout eastern Australia. Topaz contains the element fluorine, which only occurs in high concentration in a few geologic environments. Topaz usually forms along fractures and in cavities of igneous rocks like rhyolite, granite or pegmatite.
The crystals grow in the late stages of a magma cooling, when there is enough fluorine to enable the formation of topaz. Some topaz crystals grow after hot fluids hydrothermal solutions , rich in fluorine, flow through cracks in rocks that have already cooled.
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