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Fall 2023 G&G Available Now

Erica Zaidman, November 3, 2023

An overview of the Fall 2023 Gems & Gemology content.

Figure 1. These exceptional natural yellow sapphires from Madagascar (2.1–2.6 ct) represent both the Fe<sup>3+</sup> chromophore and the trapped hole paired with Fe<sup>3+</sup>. Photo by Ronnakorn Manorotkul/Lotus Gemology; courtesy of GemFever.

Yellow Sapphire: Natural, Heat-Treated, Beryllium-Diffused, and Synthetic

John L. Emmett, Ungkhana Atikarnsakul, Jennifer Stone-Sundberg, and Supharart Sangsawong, November 3, 2023

Investigates the various chromophores responsible for color in four types of yellow sapphire.

Figure 1. Yongchuliao samples collected for testing. The rough sample on the left weighs 30.1 ct, and the carving on the right weighs 12.85 ct. Photos by Shilong Xu.

Blackish Green Omphacite Jade from Guatemala

Shilong Xu, Quanli Chen, Yan Li, and Xianyu Liu, November 3, 2023

A Guatemalan jade called yongchuliao has gained popularity among Chinese buyers.

Figure 1. Iridescent andradite samples (25 ct and 125 ct) from the Lindong area of Inner Mongolia, China. As shown in the left photo, sample G-1 displays iridescence on the (211) plane but not on the (110) plane. Photos by Jiuchang Yang.

A Newly Discovered Iridescent Andradite from Inner Mongolia, China

Jiuchang Yang, Quanli Chen, Fengshun Xu, Yan Li, and Xianyu Liu, November 3, 2023

The first report of iridescent andradite from China.

Morphological features of the tourmaline crystal included in the heliodor are visible; striations and triangular growth marks are present. A band of fluid inclusions is visible near the tip of the schorl tourmaline. Photomicrograph by Rhiana Elizabeth Henry; field of view 2.90 mm. Gift of Mark Mauthner, GIA Museum no. 37772.

Heliodor with a Large Schorl Inclusion

Rhiana Elizabeth Henry, November 3, 2023

An 8.33 ct rectangular heliodor displays two tourmaline inclusions and a thin band of fluids.

Figure 1. The deep colors of green and brown augite from Dong Nai, observed in transmitted light. Top: The 9.78 g rough on the left yielded a 24.20 ct carving (24.99 cm in height). Bottom: The 11.22 g rough on the left yielded a 56.10 ct carving (36.50 cm in height). Photos by Le Ngoc Nang.

Gem-Quality Augite from Dong Nai, Vietnam

Le Ngoc Nang, Lam Vinh Phat, Pham Minh Tien, Pham Trung Hieu, Kenta Kawaguchi, and Pham Minh, August 4, 2023

Offers a comprehensive look at a variety of augite from Dong Nai, Vietnam, detailing its formation and gemological characteristics.

Figure 12. Rough and cut iolite from Blue Bear. From left to right, the faceted stones weigh 1.24, 0.48, 0.48, and 0.88 ct. Photo by Philippe Belley.

Iolite from the Thor-Odin Dome, British Columbia, Canada: Geology, Chemical Composition, Inclusions, and Cause of Chatoyancy

Philippe M. Belley, November 3, 2023

Reports on the geological setting and gemological properties of violet-blue gem cordierite from new deposits located in British Columbia.

Article

Summer 2023 G&G Available Now

Erica Zaidman, August 4, 2023

An overview of the Summer 2023 Gems & Gemology content.

Figure 1. Mammoth ivory carving with part of the brown surface retained to depict the characters. Courtesy of Duo Wang.

Origins of Color in Brown Mammoth Ivory

Zhaoying Huang, Tao Chen, Jinyu Zheng, Duo Wang, and Xing Xu, August 4, 2023

Investigates the mineral and chemical compositions and surface morphology characteristics of brown mammoth ivory to identify the origins of its brown color.

Figure 1. Suite of faceted nickel-diffused spinel (0.67–1.01 ct) showing a range of color from blue to bluish green. Photo by Aaron Palke and Diego Sanchez.

Color Modification of Spinel by Nickel Diffusion: A New Treatment

Michael Jollands, Abadie Ludlam, Aaron C. Palke, Wim Vertriest, Shiyun Jin, Pamela Cevallos, Sarah Arden, Elina Myagkaya, Ulrika D’Haenens-Johannson, Vararut Weeramongkhonlert, and Ziyin Sun, August 4, 2023

Reports on a newly discovered treatment process for producing a deep blue color in natural spinel and proposes identification criteria.

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