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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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Optimising Face-Up Appearance in Coloured Gemstone Faceting

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

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GIA’s Symmetry Grading Boundaries for Round Brilliant Cut Diamonds

A presentation of parameters used to support GIA's symmetry grading system.

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Possible “Sister” Stones of the Hope Diamond

A recent study compares a specially created model of the Hope diamond with recent computer models of the French Blue to determine if other stones could have resulted from either recutting.

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GemCad View of the French Blue Enclosed Within the Tavernier Blue
A Crystallographic Analysis of the Tavernier Blue Diamond

This study uses both historical information and modern data to create a computer model of the Tavernier Blue, orienting the finished diamond within the original diamond crystal.

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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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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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The Cullinan Diamond Centennial: A History and Gemmological Analysis Of Cullinans I And II

Eight decades after the Cullinan diamond was mined, a team of gemmologists examined the two famous gems that were created from it to become part of the Crown Jewels of England.

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A Foundation for Grading the Overall Cut Quality of Round Brilliant Cut Diamonds

The GIA diamond cut grading system described here includes the components of brightness, fire, scintillation, polish and symmetry, as well as weight and durability concerns, into a single overall grade for cut quality for standard round brilliants.

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Obtaining U.S. copyright registration for the Elara square cut-cornered brilliant diamond

The US Copyright Office granted what is believed to be the first copyright registration covering a gemstone design.

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