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An 84.90 ct sphere of Armenian turquoise measuring 23.70 × 23.88 × 23.91 mm displays a striking resemblance to planet Earth. Left: Diffuse fiber-optic lighting allows the face of the stone to be seen in full. Right: Pinpoint fiber-optic lighting creates an appearance of day and night cast onto Earth. Gifted to GIA’s colored stone reference collection by Gemfab CJSC. Photos by Britni LeCroy.

Turquoise Planet Earth

Britni LeCroy, November 3, 2023

A sphere of Armenian turquoise with natural brown matrix material mimics planet Earth.

$Figure 1. An 8.57 ct heart-shaped fracture-filled ruby treated with a zinc glass filling. Photo by Adriana Robinson.$

Translucent Ruby Filled with Zinc Glass

Shiva Sohrabi and Amy Cooper, November 3, 2023

Examination of a heart-shaped ruby reveals a zinc glass filler.

Article

Summer 2023 G&G Available Now

Erica Zaidman, August 4, 2023

An overview of the Summer 2023 Gems & Gemology content.

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.

Figure 1. The 169.05 ct filled pearl, viewed from its face (left) and base (right). Note the indented feature on the base through which the filler material was inserted prior to plugging. Photos by Gaurav Bera.

A Partially Hollow Natural Blister Pearl Filled with Foreign Materials

Roxane Bhot Jain, Abeer Alalawi, Nicholas Sturman, and Chunhui Zhou, January 25, 2023

A very large baroque white pearl is further examined in the Mumbai laboratory due to its suspicious heft.

Bismuth Glass-Filled Burmese Star Ruby

Xiaodan Jia and Mei Mei Sit, July 22, 2020

The Hong Kong laboratory recently examined a Burmese star ruby incorporating a significant amount of bismuth glass.

Figure 1. This 34.59 ct CVD-grown diamond (24.94 × 13.95 × 9.39 mm), produced by Ethereal Green Diamond in India, is the largest GIA has tested. Photo by Johnny (Chak Wan) Leung.

Article

CVD Diamond Over 34 Carats Examined in GIA’s Hong Kong Laboratory

Ka Wing Tam and Terry “Ping Yu” Poon, May 3, 2023

A look at the largest CVD diamond GIA has encountered to date.

Figure 1. Suite of faceted nickel-diffused spinel (0.674–1.009 ct) showing the range of color from blue to bluish green. Photo by Aaron Palke and Diego Sanchez.

Article

Color Modification of Spinel by Nickel (Ni) Diffusion: A New Treatment in the Gem Market

Michael Jollands, Abadie Ludlam, Aaron Palke, Wim Vertriest, Shiyun Jin, Pamela Cevallos, Sarah Arden, Elina Myagkaya, Ulrika D’Haenens-Johannson, Vararut Weeramongkhonlert, and Ziyin Sun, February 10, 2023

GIA researchers report on a new nickel-diffusion treatment used to modify color in spinel and present criteria for identification.

Figure 1. The appearance of natural high-quality turquoise and porcelain-treated turquoise. Left: Natural high-quality turquoise with various colors (the rightmost bead has a diameter of 10.0 mm). Right: Porcelain-treated turquoise with appearance and colors similar to those of natural high-quality turquoise (the smallest bead measures 6.0 × 5.0 mm). Photos by Liying Huang.

Composition and Spectral Characteristics of Porcelain-Treated Turquoise

Liying Huang, Quanli Chen, Yan Li, Zuowei Yin, Fengshun Xu, Xinxin Gao, and Yang Du, January 25, 2023

Characterizes turquoise treated with an inorganic additive that dramatically improves the luster and color of low- and medium-quality material.

Figure 1. A semitranslucent 5.72 ct red-dyed spodumene, presented as “red corundum.” Photo by Guy Borenstein.

Red-Dyed Spodumene Imitating Ruby

Guy Borenstein and Sean O’Neal, January 25, 2023

Testing identifies a “red corundum” sample as red-dyed spodumene.

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