A Gemological Institute of America scale for these runs from D, colorless, to Z, light yellow
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GIA 4Cs Color D-to-Z  The color grade of most gem-quality diamonds is based on the absence of color. ... The scale begins with the letter D, representing colorless, and continues with increasing presence of color to the letter Z, or light yellow or brown. ... But these slight differences make a very big difference in diamond quality and price.
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GIA 4Cs colour D-to-Z  The colour grade of most gem-quality diamonds is based on the absence of colour. ... shops run from colourless to near-colourless, with slight hints of yellow or brown. ... with increasing presence of colour to the letter Z, or light yellow or brown. ... Before GIA developed the D-Z Colour Grading Scale, a variety of other...
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Color | Everything Diamond  Oct 1, 2013 ... These include deeper yellows, browns and grays, plus all shades of other colors. Diamonds are colored naturally ... The Gemological Institute of America (GIA) developed the most widely used color grade scale. It runs from D (colorless) through Z (light yellow, brown or gray). Each grade represent a closely...
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4Cs | Everything Diamond  Oct 1, 2013 ... The Gemological Institute of America (GIA) developed the most widely used color grade scale. It runs from D (colorless) through Z (light yellow, brown or gray). ... These grades are adjusted to reflect the rarity of different colors. ... of America (GIA) developed the most widely used diamond clarity grade scale.
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Diamond Education - Diamondboi  Without a systematic way to evaluate and discuss these factors, there would be ... the colour grade scale developed by the Gemological Institute of America (GIA) ... It begins with D (colourless) and runs through Z (light yellow, brown or gray).
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Molecular Expressions: The Birthstone Collection - Ruby  These gemstones are red variations of the mineral corundum, a crystalline form of ... Pure corundum is a colorless, trigonal crystal, but it occurs in a wide variety of ... Rubies vary widely in color, ranging from rose red through so-called ruby red ... The American ruby, Cape ruby, Montana ruby, and Rocky Mountain ruby are...
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BERYL (Emerald, Aquamarine and other gem varieties)  Gem beryl is found nearly exclusively in hydrothermal veins, pegmatites, or at the ... Color is highly prized; weakly colored, light to medium green stone of excellent .... Most will turn blue or colorless after heat treatment, though some Brazilian...
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Mohs Scale of Hardness  In 1812 the Mohs scale of mineral hardness was devised by the German ... with a hardness of 8. 9. Corundum, Sapphire and ruby are varieties of corundum.
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Semi Precious Stones Chart - Semi Precious Stones Guide  Amazonite is a light green to light blue gemstone, supposedly named after the blue .... there are many varieties it is most often associated with the dark red version of itself. ... Birthstone: January, Zodiac Stone: Aquarius, Common, Transluscent-...
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Tiffany Yellow Diamond - Wikipedia  The Tiffany Yellow Diamond is one of the largest yellow diamonds ever discovered; its carat weight is 287.42 carats (57.484 g) in the rough when discovered in 1878 in the Kimberley mine in South Africa, ... Country of origin, South Africa ... that this was the largest diamond on display in the U.S. The famous Hope Diamond is...
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Turquoise Overview | December Birthstone - American Gem Society  Turquoise is highly esteemed for its striking namesake color and ancient history. ... Copper contributes blue hues, while iron and chrome add a hint of green. ... From ancient Egyptians to Persians, Aztecs and Native Americans, kings and...
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Gemstone Carat Weight Estimation Calculator - CSGNetwork.Com  and spelled with a "c", is a measure of weight used for gemstones. The carat weight ... One carat = .2 grams or 200 milligrams, equal to 1/5 of a gram. Stones are...
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Quartz Gemstone and Jewelry Information: Natural Quartz - GemSelect  Sep 29, 2006 ... The name 'quartz' is thought to be derived from the German word 'quarz', which .... It is closely related to citrine quartz, but is more lemon yellow in color, whereas .... Scenic agate: Agate chalcedony quartz where included dendrites resemble ... It's harder than most other materials, but still softer than popular...
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TOPAZ main - The Department of Geological Sciences  It is a birthstone for November (as is citrine) and the state gem of Texas. ... reddish-orange, but is also sometimes used (incorrectly) to denote a sherry-colored, orangish-brown. ... Sherry-brown, pink, or golden yellow topaz may show a strong orange-yellow ... Radiation + heat treatment of blue stones ubiquitous (see below).
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gem-news-2013-v1  Pala international - Palagems  Apr 17, 2013 ... Pala International's Bill Larson talks in a relaxed atmosphere .... Smithsonian receives award-winning stone .... From Reflections: A padparadscha sapphire at left, a Malaya garnet at ... by George Frederick Kunz; California as a Gem State ..... Burmese star ruby, one of our featured stones for October 2009.
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This CD accompanies the book, %3ci%3eThin-Section Petrography ...  Since obsidian is primarily natural glass, and thus is noncrystalline, it is .... stronger interference colors, the feldspars are gray or white, the chlorite is brown, and the .... green hornblende is more broken up with the amphibole cleavage lines visible. ..... polarized light, although the tremolite can sometimes have a pale color.
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Turquoise State Gem | State Symbols USA  New Mexico designated turquoise as the official state gem in 1967; one of the oldest gemstones known; an opaque, blue-to-green mineral. the robin's egg blue color is used to make gemstones. ... Turquoise and coral bola tie made by Navajo & Zuni Indians in Arizona or New Mexico; ... Turquoise stone and glass bracelet.
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Characterization and Grading of Natural-Color Yellow Diamonds  by vision scientists but may not be recognized by the layperson or .... Jean Schlumberger's jewel, Bird on a Rock) at ... diamond's yellow color (also see Anderson and Payne,. 1956). .... sometimes refers to these two appearances as lemo-.
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Opal Quality Factors - GIA  This fire opal weighs a spectacular 132 carats. ... As diverse as snowflakes or fingerprints, each gem can differ noticeably. ... Opals are often divided into types based on background color. ... Pinfire or pinpoint: Small, closely set patches of color; Harlequin or mosaic: Broad, angular, closely set patches of color; Flame:...
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How to Decide the Four C's  Diamond Helpers  Oct 13, 2014 ... AGS currently offers cut grades for Round, Princess, Oval, Cushion, and Emerald ... The Color of diamonds varies from colorless (most rare and ... VS1, VS2 clarity grades (certainly flawless to the naked eye, even to a ... Carat weight is actually the last of the four Cs to consider, surprising as this may seem.
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Gemstone and Jewelry Glossary and Terms - Jewelry Television  Rainbow andradite, a rare and exotic variety only found in Japan and Mexico, exhibits an ... Often referred to as aqua, this gemstone has been prized for many centuries. ... Beryls come in a wide variety of colors including greens (emerald), blues ... is a medium slightly yellowish-green stone speckled with orangy red spots.