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Gerd Dreher agate lily and Patrick Dreher citrine mouse
Gem Virtuosos: The Drehers and Their Extraordinary Carvings

A look at the artistic heritage of the Drehers, an influential family of gem carvers in Idar-Oberstein, Germany.

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Various colors of nephrite
Characterization of Mg and Fe Contents in Nephrite Using Raman Spectroscopy

Evaluates the usefulness of Raman spectroscopy in distinguishing the color varieties of nephrite based on the relative ratio of Mg to Fe concentration.

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The Wittelsbach Blue

This article describes what is known about the Wittelsbach Blue since it was first reported in 1666, and the gemological information released to date on this diamond.

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Ruby and Sapphire Production and Distribution: A Quarter Century of Change
Ruby and Sapphire Production and Distribution: A Quarter Century of Change

During the past 25 years, the corundum market has been transformed from one of medium to high-priced gems to one that encompasses nearly all price ranges.

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Whitish Graining with an Amorphous Appearance
The Impact of Internal Whitish And Reflective Graining on the Clarity Grading of D-To-Z Color Diamonds at the GIA Laboratory

This article reviews the GIA Laboratory’s history of reporting on certain types of graining which are often the only characteristics present in large, high-clarity, high-color diamonds.

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Color Grading “D-to-Z” Diamonds at the GIA Laboratory

This article discusses the history and ongoing development of GIA's color grading system, and explains how its laboratory applies it.

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Optimizing Face-Up Appearance in Colored Gemstone Faceting

How contrast patterns can increase perceived brightness and optimize a gemstone's appearance.

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An Examination of Four Important Gems

Several famous and historical gemstones in the Smithsonian's collection are examined and reported on.

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Characterization and Grading of Natural-Color Yellow Diamonds

A large number of natural-color yellow diamonds are analyzed using grading and appearance aspects among other characteristics to clarify the differences between them and the light yellow diamonds associated with GIA's D-to-Z color grading scale.

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Characterization and Grading of Natural-Color Pink Diamonds

Known for their great beauty and rarity, pink diamonds have long been sought after by jewelers, collectors, and consumers.

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