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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
Characterisation of Mg and Fe Contents in Nephrite Using Raman Spectroscopy

Evaluates the usefulness of Raman spectroscopy in distinguishing the colour 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 gemmological information released to date on this diamond.

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Star of the South: A Historic 128 Ct Diamond

This article presents the first complete gemmological characterisation of the historic 128.48 ct Brazilian diamond known as the Star of the South.

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Characterisation and Grading of Natural-Colour Pink Diamonds

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

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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 Colour 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-colour diamonds.

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A History of Diamond Treatments

Modern gemmologists and diamantaires are faced with a broad spectrum of colour and clarity treatments ranging from the simple to the highly sophisticated.

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

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

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Characterisation and Grading of Natural-Colour Yellow Diamonds

A large number of natural-colour yellow diamonds are analysed 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 colour grading scale.

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