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Diamond

Diamonds are among nature’s most precious and beautiful creations.

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Color

Colorless diamonds are scarce—most diamonds have tints of yellow or brown.

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4Cs

Factors used to describe diamonds: Clarity, Color, Cut, Carat Weight

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Rarity

The rarity of one or more of the 4Cs can affect value.

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Octahedron

The crystal shape of a gem diamond is often the octahedron.

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Trigons

Trigons—little triangular depressions—occur only on octahedral faces.

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Growth marks

Diamond’s growth marks help experts separate diamonds from simulants.

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Tools

Research

A piece of diamond rough with green body color and triangular etchings on the surface.
Article
GIA Researchers Reveal the Secrets to Diamond-in-a-Diamond Mystery

GIA researchers in NY recently had the opportunity to examine one of the most interesting and unique diamond crystals ever found.

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Patrick O’Shea stands in front of a staircase at the Javits Center in New York City.
Article
The Curious Life of Patrick O’Shea: From Ballistics Detective to Gemologist and Jewelry Designer

Patrick O’Shea’s life’s journey has led him down many career paths until they all came together as a designer who specializes in masonic jewelry.

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A multi-diamond brooch.
Article
2019 in Review: Diamond Trade Begins Recovery, Jewelry Retail Blooms Late, Extraordinary Auction Sales

2019: A year of ups and downs in the gem and jewelry industry, including diamonds, retail, auction sales and laboratory-grown diamonds.

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A face-up view of a cushion cut diamond with blue color.
Article
Gems & Gemology’s 7 Most Unusual Encounters from 2019

Check out some of the most interesting and unusual diamonds and colored stones submitted to GIA’s laboratories in 2019.

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A rectangular cut Fancy Deep blue diamond is framed by two pear shaped diamonds.
Article
Diamond Market in Recovery, Top-end Auction Results

World’s two largest diamond producers say market is stabilizing after several months of severe cutbacks in rough sales. Christie’s and Sotheby’s sales.

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Green diamond, color-treated by multi-step process
Hydrogen-Rich Green Diamond Color-Treated by Multi-Step Processing

Characterization of an intense yellowish green faceted diamond revealed a complex treatment process.

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Gemstones in the Era of the Taj Mahal and the Mughals

A look at the gem ornamentation of this landmark, as well as the jewels of the Mughal dynasty.

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The Black Orlov and two Fancy white diamonds
Natural-Color Fancy White and Fancy Black Diamonds: Where Color and Clarity Converge

A systematic study of the properties of approximately 500 Fancy white and 1,200 Fancy black diamonds.

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A row of various shaped cut and polished pink diamonds.
Article
Why are Pink Diamonds Pink? GIA Researchers Dive Deep into their Crystal Structure

GIA researchers analyzed more than 90,000 natural pink diamonds to better understand how these rare and beautiful diamonds formed and got their color.

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A diamond necklace that features a 100.02 Fancy Intense yellow diamond. The pendant is done in the shape of a musical instrument.
Article
Bullish Predictions for 2019 Holiday Sales Despite Concerns, Sotheby’s Hong Kong Auction Sales

U.S. holiday sales predictions are better than expected. Sotheby’s Hong Kong auction features a 100 ct yellow diamond necklace by GIA alumna Anna Hu.

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