News & Articles

Spring 2023 G&G Available Now

Erica Zaidman, May 23, 2023

An overview of the Spring 2023 Gems & Gemology content.

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.

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.

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.

Winter 2022 G&G Available Now

Brooke Goedert, January 25, 2023

An overview of the Winter 2022 Gems & Gemology content.

Figure 1. A padparadscha sapphire (3.54 ct) submitted to the GIA laboratory increased its orange color during the color stability test. If left in the dark for an extended period of time, the color could become less orange or even go to straight pink. This can be replicated by exposing the sapphire to intense LED illumination. This stone would be characterized as a padparadscha sapphire because the pink-orange color after the stability test is acceptable. Photos by Diego Sanchez.

An Update on Sapphires with Unstable Color

Aaron C. Palke, Shane F. McClure, and Nathan R. Renfro, December 12, 2022

Unexpected behavior is observed in sapphires submitted to GIA for color stability testing.

Fall 2022 G&G Available Now

Brooke Goedert, November 11, 2022

An overview of the Fall 2022 Gems & Gemology content.

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