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Fancy Dark brown to Fancy black Marange diamonds
Black Diamonds from Marange (Zimbabwe): A Result of Natural Irradiation and Graphite Inclusions

Characterises a suite of 40 natural brown to black diamonds from this deposit so that they can be distinguished from suspected treated black diamonds.

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Suite containing over 36 carats of Yogo sapphire
Gemmological Characterisation of Sapphires from Yogo Gulch, Montana

A look at the mining and distinguishing characteristics of this naturally vibrant blue sapphire.

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Micro-Features of Ruby
Inclusions in Natural, Synthetic and Treated Ruby

Provides a visual guide to the internal features of natural, synthetic and treated rubies.

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Drilled natural pearls examined in this study.
Saltwater Pearls from the Pre- to Early Columbian Era: A Gemmological and Radiocarbon Dating Study

Examines 85 saltwater natural pearls, reportedly harvested from the Caribbean islands off the coast of Venezuela during the early 16th century, to determine their age.

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Rough CLIPPIR diamonds
The Very Deep Origin of the World’s Biggest Diamonds

Explores an exceptional family of diamonds, referred to as “CLIPPIR” (Cullinan-like, Large, Inclusion-Poor, Pure, Irregular and Resorbed), that formed in a super-deep environment.

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A blue synthetic star sapphire from past production of Wiede’s Carbidwerk
Synthetic Star Sapphires and Rubies Produced by Wiede’s Carbidwerk, Freyung, Germany

Details the process used by Wiede’s Carbidwerk to produce star synthetic corundum from the mid-1950s until the 1970s.

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Samples of by-product synthetic zincite
Characteristics of Gem-Quality By-Product Synthetic Zincite

Investigates the properties of synthetic zincite produced by industrial kilns in Poland.

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A 0.11 ct faceted grandidierite from Madagascar
A New Deposit of Gem-Quality Grandidierite in Madagascar

Reviews the properties of exceptionally pure grandidierite from a new source.

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Color zoning in amethyst from Boudi, Morocco
Amethyst from Boudi, Morocco

An introduction to Moroccan amethyst, which features distinctive color zoning and inclusions.

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Emeralds from Musakashi, Zambia
Three-Phase Inclusions in Emerald and Their Impact on Origin Determination

Discusses the role of three-phase inclusions in emerald, in combination with spectroscopy and trace-element analysis, in determining geographic origin.

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