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Amethyst: An Intoxicating Purple Gem

February Birthstone

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Heat Treatment of Burmese Ruby, Copper-Diffused Red Feldspar, and Porcelain-Treated Turquoise

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Figure 1. A faceted heated ruby from Mogok, Myanmar, weighing more than 3 ct, stands out against a backdrop of untreated ruby rough from the same origin. The striking appearance of Mogok ruby is highly sought after. Photo by Wimon Manorotkul; faceted ruby courtesy of Kiarttichatra Intarungsee.
Feature

Low Temperature Heat Treatment of Burmese Ruby

Documents heating experiments conducted on Burmese rubies to find useful indicators of heat treatment at temperatures below 1200°C.
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GIA Knowledge Sessions

Engage in webinars on the most diverse and pressing issues in gemology today, including gemstone origin, laboratory-grown stones and new discoveries in field gemology.
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Figure 1. An unusually large cat’s-eye emerald weighing approximately 126 ct. Photo by Shunsuke Nagai.
Lab Notes

An Extraordinarily Large Cat’s-Eye Emerald

The Tokyo laboratory examines a 126 ct cat’s-eye emerald from Brazil.
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Figure 1. Fibers of serpentine were observed throughout this demantoid garnet in an unusual randomly curved pattern. Photomicrograph by Shunsuke Nagai; field of view 2.00 mm.
Micro-World

Unusual “Horsetail” and Columnar Inclusions in Demantoid

Examination of a yellowish green demantoid reveals fibers of serpentine in a randomly curved pattern and a columnar two-phase negative crystal.
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Figure 1. These examples of gem minerals that formed in magmatic environments are part of GIA’s Eduard Gübelin Collection. From top to bottom and left to right: 29.96 ct sanidine feldspar from Germany, 53.00 ct peridot from Myanmar, 11.58 ct zircon from Thailand, 20.66 ct topaz from Utah, 2.05 ct sapphire from Thailand, 18.36 ct pyrope garnet from the Czech Republic, 19.55 ct black spinel from Thailand, and 2.50 ct ruby from Thailand. Photos by Robert Weldon.
Colored Stones Unearthed

Gems Formed in Magmatic Rocks

This installment of “Colored Stones Unearthed” covers gemstones that formed in magmatic environments and the insights they offer into the evolution of the earth and the geological processes that shaped our world.
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Figure 1. GSA 2022 oral and poster presenters. Left to right: Elina Myagkaya, Shiyun Jin, Che Shen, Stephanie Persaud, Roy Bassoo, Rhiana Henry, Alexander Goodsuhm, Rachelle Turnier, Yusuke Katsurada, Mei Yan Lai, Matthew Hardman, Christopher Breeding, Evan Smith, and Peter Heaney. Photo by Robert Weldon.
Gem News International

GSA 2022 Annual Meeting

An overview of GIA’s presentations at the annual Geological Society of America (GSA) meeting held in Denver, Colorado.
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Gems & Gemology
This Month's

Featured Gems

Featured Gem Peridot
Peridot

Found in lava, meteorites, and deep in the earth’s mantle, yellow-green peridot is the extreme gem.
Fancy Color Diamond
Fancy Color Diamond

Dazzling brilliance. Captivating color. These are the planet’s most valued gems.
Diamond
Diamond

Diamonds are among nature’s most precious and beautiful creations.
Emerald Bluish Green Stone
Emerald

Emerald is the bluish green to green variety of beryl, a mineral species that includes aquamarine.
Featured Gem Citrine
Citrine

Citrine is the transparent, pale yellow to brownish orange variety of quartz.

View the Gem Encyclopedia