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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.

Gerd Dreher agate lily and Patrick Dreher citrine mouse

Gem Virtuosos: The Drehers and Their Extraordinary Carvings

Robert Weldon, Cathleen Jonathan, and Rose Tozer, January 26, 2018

A look at the artistic heritage of the Drehers, an influential family of gem carvers in Idar-Oberstein, Germany.

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.

Origin Determination of Dolomite-Related White Nephrite through Iterative-Binary Linear Discriminant Analysis

Zemin Luo, November 22, 2015

A technique for origin identification based on statistical analysis and LA-ICP-MS spectrometry.

Characterisation of Mg and Fe Contents in Nephrite Using Raman Spectroscopy

Xiaoyan Feng, Yong Zhang, Taijin Lu, and Hui Zhang, August 7, 2017

Evaluates the usefulness of Raman spectroscopy in distinguishing the colour varieties of nephrite based on the relative ratio of Mg to Fe concentration.

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.

Useful Visual Clue Indicating Corundum Heat Treatment

John I. Koivula, October 19, 2013

A demonstration of the conversion of limonitic residues to hematite in surface-reaching.

Cutting Diffraction Gratings to Improve Dispersion (“Fire”) in Diamonds

Al Gilbertson, Benjamin Gudlewski, Mary Johnson, George Maltezos, Axel Scherer, and James Shigley

A new microlithography process developed to create high-resolution diffraction grating patterns on portions of certain facets can improve the dispersion of light and thus the amount of “fire” in a diamond.

Characterisation of “Green Amber” With Infrared and Nuclear Magnetic Resonance Spectroscopy

Ahmadjan Abduriyim, et al.

A peridot-like bright greenish yellow to green gem material called “green amber” has recently appeared in the gem market.

Gem-Quality Andalusite from Brazil

Shyamala Fernandes and Gagan Choudhary

Widely known as a rock-forming mineral, andalusite is not frequently encountered as a gem material.

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