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Gemstones

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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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Accurate Reporting of Key Trace Elements in Ruby and Sapphire Using Matrix-Matched Standards

Presents a group of corundum standards developed by GIA to improve the accuracy and efficiency of its laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) instruments.

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Beryllium Diffusion of Ruby and Sapphire

The heat treatment of corundum involving lattice diffusion of beryllium (Be) at temperatures over 1800°C has become a major issue in the gem trade.

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Rubies and Fancy Sapphires from Vietnam
Rubies and Fancy Sapphires from Vietnam

Gem-quality rubies and pink to purple sapphires are being recovered from the Luc Yen and Quy Chau mining regions of Vietnam.

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Heat Treating Corundum: The Bangkok Operation

An overview of the potential effects that heat treatment can have on corundum.

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The Seven Types of Yellow Sapphire and Their Stability to Light

The authors determined that there are actually seven types of "yellow" sapphire on the market today, which differ in the cause of colour and the stability of the colour to light.

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Some Diagnostic Features of Russian Hydrothermal Synthetic Rubies and Sapphires

Most Russian hydrothermal synthetic rubies and pink, orange, green, blue and violet sapphires—coloured by chromium and/or nickel—reveal diagnostic zigzag or mosaic-like growth structures associated with colour zoning.

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The Sapphires of Mingxi, Fujian Province, China

Blue sapphires from China are similar to gem corundum from Australia, Thailand, and Kampuchea (Camodia).

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The Separation of Natural from Synthetic Colourless Sapphire

Greater amounts of colourless sapphire—promoted primarily as diamond substitutes, but also as natural gemstones—have been seen in the gem market during the past decade.

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Rubies and Fancy-Colour Sapphires from Nepal

Gem-quality rubies and fancy-colour sapphires have been recovered from dolomite marble lenses located high in the Himalayan mountains of east-central Nepal (Ganesh Himal).

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