Article Search Results

A face-up view of a cushion cut diamond with blue color.

Article

Gems & Gemology’s 7 Most Unusual Encounters from 2019

Stuart Overlin, Brooke Goedert and Kellie Giordano, December 13, 2019

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

Optical defects in diamond: a quick reference chart

James E. Shigley, July 24, 2013

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

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

Yun Luo, July 24, 2013

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

Grey-To-Blue-To-Violet Hydrogen-Rich Diamonds from the Argyle Mine, Australia

Carolyn H. van der Bogert, Christopher P. Smith, Thomas Hainschwang, and Shane F. McClure

The Argyle diamond mine is the only known source of type IaB hydrogen- and nitrogen-rich diamonds coloured grey to blue to violet.

Article

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

Russell Shor, June 12, 2015

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

Article

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

Russell Shor, August 14, 2015

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

Coloured Diamonds in the Aurora Butterfly of Peace Collection

The “Type” Classification System of Diamonds and Its Importance in Gemmology

Christopher M. Breeding and James E. Shigley, June 1, 2009

Knowledge of type allows gemmologists to better evaluate if a diamond might be treated or synthetic, and whether it should be sent to a laboratory for testing.

Treated-Colour Pink-To-Red Diamonds from Lucent Diamonds Inc.

Wuyi Wang, Christopher P. Smith, March 1, 2005

Using a multi-step process, Lucent Diamonds has developed a new treatment process for certain natural diamonds that creates colours from pink-purple to red to orangey brown.

Detection of Treatment in Two Unusual Green Diamonds

Emmanuel Fritsch, James E. Shigley, September 1, 1988

A pair of sharp absorption bands in the near-infrared region, referred to as H1b and H1c, have been detected in one (and the H1b band in the other) of two green diamonds known to have been treated.

Mixed-Type Cape Diamond

Martha Altobelli and Paul Johnson , October 31, 2014

A Fancy orangey-yellow “cape” diamond featured an unexpected 480 nm band, a defect normally associated with orange colour.

Article Search Results

Types

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Gemstones

Article Search Results

Types

Content Type

Reviewed

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Gemstones

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