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The Beauty and Value of Inclusions, Plus Double Stars and Corundum from Tajikistan

Duncan Pay, July 31, 2015

We invite gemologists to take a closer look at the astounding beauty and variety of the micro-world of gems.

Cause of Color in Yellow Sapphire, Plus Characterization of Oregon Sunstone, Ukrainian Beryl, and British Columbian Iolite

Duncan Pay, November 3, 2023

An overview of the Fall 2023 Gems & Gemology content.

Miners use shovels and sluicing equipment to search for diamonds near the Vaal River in South Africa.

Article

Historical Reading List: The Diamond Fields of South Africa: Part 2 (1893-2014)

Dr. James Shigley, May 29, 2017

Within a few years of their discovery, the diamonds deposits of South Africa produced more diamonds than what had come from India in two millennia.

Article

Carbon Isotope Studies Reveal Diamond Growth History

Duncan Pay, Jim Shigley, Pedro Padua, March 26, 2014

Isotope studies at the Carnegie Institution reveal sources of carbon in diamond, plus answers to other fundamental questions.

Gem Olivine and Calcite Mineralization Precipitated from Subduction-Derived Fluids in the Kohistan Arc-Mantle (Pakistan)

P. Bouilhol, J.-P. Burg, J.-L. Bodinier, M. Schmidt, S. Bernasconi, and H. Dawood, The Canadian Mineralogist, Vol. 50, No. 5, 2012, pp. 1291–1304, http://dx.doi.org/10.3749/canmin.50.5.1291.

Geochemical data presented suggests remobilized CO₂ and H2₂O from a subducted island arc helped form the calcite + olivine-bearing veins in Kohsitan, Pakistan.

Figure 1. A fine 925 ct crystal that was formerly displayed in the Texas State Capitol and sat on the governor’s desk in 1969 when the legislature adopted blue Texas topaz as the state gem. This specimen was found in 1904 and now resides in the Hamman Gem and Mineral Gallery in the Department of Earth and Planetary Sciences at the University of Texas at Austin (catalog no. B0344). Photo by Blanca Espinoza.

Topaz from Mason County, Texas

Roy Bassoo, Diane Eames, Matthew F. Hardman, Kenneth Befus, and Ziyin Sun, January 26, 2024

A comprehensive look at Texas topaz, detailing its gemological and compositional characteristics and providing a basis for using trace element concentrations to identify its origin.

Review of Pegmatites and Their Gem Minerals, by Michael Menzies and Jeffrey Scovil.

Book Review: Pegmatites and Their Gem Minerals

James E. Shigley, November 3, 2022

Review of Pegmatites and Their Gem Minerals by Michael Menzies and Jeffrey Scovil.

Figure 5. Two emerald specimens from quartz-calcite veins. A and B: Specimen containing emeralds and associated minerals such as white calcite, off-white quartz, and brown phlogopite. The calcite fluoresces moderately red (early crystallization, larger particles) and strongly blue (later filling crystallization, xenomorphic granular and smaller) under short-wave ultraviolet light. C: Emeralds with associated minerals such as white calcite, white or gray quartz, gray phenakite, and brown phlogopite. Photos by Sheng-Hao Zhu (A) and Yi Guo (B and C).

Characterization of Emeralds from Zhen’an County in Shaanxi, China

Yi Guo, Xiao-Yan Yu, and Yu-Yu Zheng, February 2, 2026

Presents a comprehensive analysis of the gemological, spectroscopic, and trace element characteristics of a set of Shaanxi emerald samples based on standard and advanced gemological methods.

Update on Rock Creek Sapphire Deposit

Warren Boyd and Keith Barron, July 31, 2015

An overview of recently expanded sapphire production at the Gem Mountain mine near Philipsburg, Montana.

Diamond Geology

December 4, 2018

Abstracts of speaker presentations from the “Diamond Geology” session of GIA’s 2018 International Gemological Symposium.

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