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Figure 1. One of GIA’s new LA-ICP-MS corundum calibration standards sets (set number 1); the epoxy disk containing the set is 1.5 inches in diameter. NIST SRM 610 and 612 glass standards are included to account for trace and non-trace elements, such as those found in inclusions, that were not incorporated into the synthetic sapphire crystals grown for standards. Photo by Jennifer Stone-Sundberg.

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

Jennifer Stone-Sundberg, Timothy Thomas, Ziyin Sun, Yunbin Guan, Zachary Cole, Randy Equall, and John L. Emmett, January 26, 2018

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.

Real-Time Microradiography of Pearls: A Comparison Between Detectors

Stefanos Karampelas, Abeer Tawfeeq Al-Alawi, and Ali Al-Attawi, January 26, 2018

Compares the image quality provided by real-time microradiographic imaging (RTX) units fitted with two different detectors: an image intensifier (II) and a flat panel detector (FPD).

Emerald crystals from Colombia, Afghanistan, and Zambia

Photoluminescence Spectra of Emeralds from Colombia, Afghanistan and Zambia

D. Brian Thompson, Christian J. Bayens, Matthew B. Morgan, Taylor J. Myrick, and Nealey E. Sims, November 8, 2017

Compares PL spectroscopy data of 48 emerald samples from three countries to evaluate the usefulness of the technique in geographic origin determination.

Book Review: From a Snowflake to an Iceberg: The McFerrin Collection

Dorothy McFerrin, publ. by the McFerrin Foundation, College Station, Texas, 2013, US $125, October 19, 2013

By Dorothy McFerrin, publ. by the McFerrin Foundation, College Station, Texas, 2013, US $125 (£74)

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.

GIA’s Symmetry Grading Boundaries for Round Brilliant Cut Diamonds

Ron H.Geurts, Ilene M. Reinitz, Troy Blodgett, and Al M. Gilbertson, December 1, 2011

A presentation of parameters used to support GIA's symmetry grading system.

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.

Colour Grading “D-to-Z” Diamonds at the GIA Laboratory

John M. King, December 1, 2008

This article discusses the history and ongoing development of GIA's colour grading system, and explains how its laboratory applies it.

Star of the South: A Historic 128 Ct Diamond

Christopher P. Smith and George Bosshart, March 1, 2002

This article presents the first complete gemmological characterisation of the historic 128.48 ct Brazilian diamond known as the Star of the South.

Portable Instruments and Tips on Practical Gemmology in the Field

Edward W. Boehm, March 1, 2002

Buying gems or jewellery can be challenging even when one has access to a fully equipped lab.

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