Metal Sulfide in Spinel

  • Date: 2026-02-03

A strikingly textured crystal is suspended within a pink spinel.

 metal sulfide crystal in spinelFigure 1. A strikingly textured crystal, likely a metal sulfide, is suspended within a pink spinel; viewed under darkfield and diffuse fiber-optic lighting. The step-cut facets on the stone’s pavilion provide a sense of depth to the image. Photomicrograph by E. Billie Hughes; field of view 3.4 mm; courtesy of Pamir Gems.

Recently, a 3.14 ct pink spinel was submitted to the Lotus Gemology laboratory, with encouragement from the owner to examine its inclusions. When viewed under the microscope, the spinel did not disappoint. Suspended within was a richly textured, opaque metallic crystal (figure 1). Although attempts were made to identify the inclusion using micro-Raman spectroscopy, its identity remained inconclusive. However, based on the crystal’s appearance, it was likely a metal sulfide. Similar inclusions in spinel have been reported as pyrite (E.B. Hughes et al., “Spinel inclusions: An exercise in aesthetics,” InColor, No. 43, 2019, pp. 66–73; N. Renfro et al., “Micro-features of spinel,” Spring 2021 G&G, pp. 46–49).

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About the Author

E. Billie Hughes visited her first gem mine (in Thailand) at age two and by age four had visited three major sapphire localities in Montana. A 2011 graduate of UCLA, she qualified as a Fellow of the Gemmological Association of Great Britain (FGA) in 2013. An award winning photographer and photomicrographer, she has won prizes in the Nikon Small World and Gem-A competitions, among others. Her writing and images have been featured in books, magazines, and online by Forbes, Vogue, National Geographic, and more. In 2019 the Accredited Gemologists Association awarded her their Gemological Research Grant. Billie is a sought-after lecturer and has spoken around the world to groups including Cartier and Van Cleef & Arpels. In 2020 Van Cleef & Arpels’ L’École School of Jewellery Arts staged exhibitions of her photomicrographs in Paris and Hong Kong.

Notes

This article first appeared in Gems & Gemology, Winter 2025, Vol. 61, No.4, p. 404.

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