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Figure 1. Greenland’s rubies are characterized by abundant twinning planes. The twinning planes are not altered by the treatment at a larger scale, but features associated with the twinning can be significantly affected by heating. Photo by S. Wongchacree; field of view 14.40 mm.

Characteristics of Treated Rubies from Greenland

Martin Viala, Wim Vertriest, Charuwan Khowpong, and Suwasan Wongchacree, August 4, 2023

An overview of the treatment process of ruby and pink sapphire from Greenland and its effect on inclusion scenes and chemistry.

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Spring 2023 G&G Available Now

Erica Zaidman, May 23, 2023

An overview of the Spring 2023 Gems & Gemology content.

Figure 1. Top production from Rock Creek from the 2021 mining season, in rough and cut form. The rough stones range from 10.05 to 67.15 ct and the faceted stones from 3.09 to 12.18 ct. The yellow sapphire at top center was named the Yellowstone sapphire and is part of the Somewhere in the Rainbow collection. For the faceted stones, the blue stone on the left and the two blue stones on the bottom are heated, while the others are unheated. Note that one of the rough stones is missing in the faceted stone layout. Photos by Robert Weldon; courtesy of Potentate Mining, LLC.

Gemological Characterization of Montana Sapphire from the Secondary Deposits at Rock Creek, Missouri River, and Dry Cottonwood Creek

Aaron C. Palke, Nathan D. Renfro, Jeffrey R. Hapeman, and Richard B. Berg, May 23, 2023

Examines the mining history and geological characteristics of the three secondary sapphire deposits in the state of Montana, as well as the properties of these sapphires (unheated and heat-treated).

Figure 1. An aegirine crystal inclusion in poudretteite rough from Mogok, viewed with oblique fiber-optic illumination. Photomicrograph by Kyaw Thu; field of view 2.3 mm.

Aegirine in Poudretteite

Kyaw Thu, January 25, 2023

Aegirine inclusions are observed in two samples of poudretteite from Mogok.

Figure 1. An unusually large cat’s-eye emerald weighing approximately 126 ct. Photo by Shunsuke Nagai.

An Extraordinarily Large Cat’s-Eye Emerald

Makoto Miura, January 25, 2023

The Tokyo laboratory examines a 126 ct cat’s-eye emerald from Brazil.

Article

Fall 2022 G&G Available Now

Brooke Goedert, November 11, 2022

An overview of the Fall 2022 Gems & Gemology content.

The Geographic Origin of Diamonds, Sapphire from China, and Pigments Sourced from Gem Materials

Duncan Pay, October 21, 2022

An overview of the Fall 2022 Gems & Gemology content.

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