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Three pieces of labradorite with yellow, blue and green flashes of color.
Article
Optical Effects of Phenomenal Cabochons

Learn how the structure, inclusions and properties of some gemstones interact with light to create unusual visual effects.

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A face-up view of a cushion cut diamond with blue color.
Article
Gems & Gemology’s 7 Most Unusual Encounters from 2019

Check out some of the most interesting and unusual diamonds and coloured stones submitted to GIA’s laboratories in 2019.

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Multi-colored gems are superimposed on an image of glacier peaks.
Article
Gems and Minerals from the Sub-Arctic

Circumnavigate the boreal reaches of the globe to explore gems from polar regions.

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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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Article
Pyrope Garnet and Montana Sapphires Highlight Winter 2015 G&G

G&G Brief presents an overview of the content of the Winter 2015 issue of Gems & Gemology.

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Optical defects in diamond: a quick reference chart

A simple chart of optical defects in diamond, including those that produce colouration and fluorescence colours.

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Fluorescence produced by optical defects in diamond: measurement, characterisation and challenges

How variations in UV lamp output can affect observed fluorescence colour and intensity.

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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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Article
Spring 2015 G&G Examines Blue Spinel, Chinese Jewellery Design and the Latest in Synthetics

G&G Brief presents an overview of the content of the Spring 2015 issue of Gems & Gemology.

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Article
Summer 2015 G&G: Dual-Stars, Photomicrography Guide, Rubies from Tajikistan, New Micro-World Section

G&G Brief presents an overview of the content of the Summer 2015 issue of Gems & Gemology.

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