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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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A wide range of jewelry pieces with the round brilliant diamond cut
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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Computer Rendering of the “French Blue” Diamond
The French Blue and the Hope: New Data from the Discovery of a Historical Lead Cast

With the use of modern tools and technology, this article sheds light on the history and provenance of both the French Blue and the Hope diamonds.

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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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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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15 ct tanzanite
Pleochroism in Faceted Gems: An Introduction

Describes the phenomenon of pleochroism and its complex effect on the appearance of colored stones.

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Faceting Large Gemstones

The techniques for cutting and polishing gemstone giants.

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Curves and Optics in Nontraditional Gemstone Cutting

A series of cuts, designed by the author, exhibit extraordinary optical effects that result from a combination of curved surfaces and plane facets placed to take advantage of internal reflection.

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An Extraordinary Calcite Gemstone

The unusual effects of dispersion and twinning produced by a calcite gemstone.

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Gem-Quality Red Beryl from the Wah Wah Mountains, Utah

The unique mineralogical and gemological character of gem-quality red beryl from Utah.

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