Article Search Results

Reversible Colour Modification of Blue Zircon by Long-Wave Ultraviolet Radiation

Nathan D. Renfro, November 7, 2016

Determines whether blue zircon, inadvertently altered to brown by exposure to long-wave UV radiation, can be restored to its original colour through the use of incandescent light.

Vanadium and Chromium-Bearing Pink Pyrope Garnet: Characterisation and Quantitative Colorimetric Analysis

Ziyin Sun, Aaron C. Palke, and Nathan Renfro, February 1, 2016

This type of pink pyrope garnet, believed to have been mined in Tanzania, shows a distinct colour-change phenomenon resulting from its unique chemical composition.

Suite containing over 36 carats of Yogo sapphire

Gemmological Characterisation of Sapphires from Yogo Gulch, Montana

Nathan D. Renfro, Aaron C. Palke, and Richard B. Berg, August 6, 2018

A look at the mining and distinguishing characteristics of this naturally vibrant blue sapphire.

Fancy Dark brown to Fancy black Marange diamonds

Black Diamonds from Marange (Zimbabwe): A Result of Natural Irradiation and Graphite Inclusions

Karen V. Smit, Elina Myagkaya, Stephanie Persaud, and Wuyi Wang, August 6, 2018

Characterises a suite of 40 natural brown to black diamonds from this deposit so that they can be distinguished from suspected treated black diamonds.

Recently discovered and legendary diamonds in the blue/gray/violet color range

Natural-Colour Blue, Grey and Violet Diamonds: Allure of the Deep

Sally Eaton-Magaña, Christopher M. Breeding, and James E. Shigley, August 6, 2018

Summarises data collected on more than 15,000 natural blue/grey/violet diamonds examined by GIA during the last decade and examines the mechanisms that produce this colour range.

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.

The Very Deep Origin of the World’s Biggest Diamonds

Evan M. Smith, Steven B. Shirey, and Wuyi Wang, November 8, 2017

Explores an exceptional family of diamonds, referred to as “CLIPPIR” (Cullinan-like, Large, Inclusion-Poor, Pure, Irregular and Resorbed), that formed in a super-deep environment.

True Colours of “Dalmatian Jasper”

Tomasz Powolny and Magdalena Dumańska-Słowik, November 8, 2017

Discusses the mineralogical composition and provenance of this spotted decorative gemstone.

Drilled natural pearls examined in this study.

Saltwater Pearls from the Pre- to Early Columbian Era: A Gemmological and Radiocarbon Dating Study

Chunhui Zhou, Gregory Hodgins, Todd Lange, Kazuko Saruwatari, Nicholas Sturman, Lore Kiefert, and Klaus Schollenbruch, November 8, 2017

Examines 85 saltwater natural pearls, reportedly harvested from the Caribbean islands off the coast of Venezuela during the early 16th century, to determine their age.

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.

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