by E. Billie Hughes, John I. Koivula, Wimon Manorotkul, Nathan Renfro and Richard W. Hughes
Inclusions in Spinel • An Exercise in Aesthetics


To the jeweler, spinel is famous for its vivid colors. But for the gemologist, this gem is unlike any other. Its extreme hardness allows a fine polish. Couple this with single refraction, which eliminates the image blurring found in most other gems, and a varied landscape of inclusion subjects, results in an unparalleled canvas of delight for the photomicrographic artist.

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by Richard W. Hughes, Auslan Ishmael, Flavie Isatelle & Peter Wang

The history of the Lao sapphire mines at Ban Huay Xai is detailed, along with modern mining by Hong Kong based Sino Resources Mining Corp. Ltd. from 2006–2012.

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by Richard W. Hughes, with E. Billie Hughes & Wimon Manorotkul
Colored Stone Grading • A Heretic's Guide

Developing a comprehensive colored stone grading system has been the dream of gemologists since the late 1970's, but despite a number of valient attempts, we are no closer to the goal today than we were four decades ago. This article examines the various problems of colored stone grading, explaining why the challenges are at least an order of magnitude greater than the grading of diamonds.

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by E. Billie Hughes

A Burmese sapphire shows a celestial scene both externally and internally.

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by [see below for authors]
Sapphire Squeeze • Corundums treated with high temperatures and low pressure

27 February 2019: Sapphires heated with high temperatures and low pressures (~1kbar) first entered the market in 2009, becoming more common since 2016. This article examines the process in detail and looks at the question of whether a separate disclosure is needed for the treatment.

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by E. Billie Hughes

An included calcite crystal within an unheated Burmese ruby displays dramatic twinning planes.

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by E. Billie Hughes

Surface-reaching growth tubes in a sapphire provide insight into the gem’s origin and treatment history.

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by E. Billie Hughes
Oiled Ruby

A ruby’s surface-reaching cavity is filled with red oil.

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by Richard W. Hughes
Crystal Optics • Gem and Crystal Optical Properties • Lotus Gemology

The optical properties of crystals are intimately related to their crystal structures. This article examines the precise relationship between optic character and sign and crystal structure.

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by E. Billie Hughes
Beyond Octahedra • Inclusions in Spinel

A look into the world of spinel inclusions that goes beyond simple octahedral crystals.

 

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