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September 2023 Birthstone

Sapphire: A History of
Romance & Royalty

September Birthstone

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Scholarships for Gemology &
Jewelry Arts Courses

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SU23 G&G Issue Cover

Nickel-Diffused Spinel, Vietnamese Augite, and
Brown Mammoth Ivory

New Gems & Gemology Issue

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featured

Research & News

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.
Feature

Nickel-Diffused Spinel

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

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. 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.
Lab Notes

CVD Diamond Over 34 Carats

A look at a 34.59 ct CVD-grown diamond examined at GIA’s Hong Kong laboratory.
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These iridescence features observed in a 1.71 ct natural diamond (top) were reminiscent of Rainbow Mountain in Peru (bottom). Photomicrograph by Tejas Jhaveri; field of view 2.90 mm. Bottom photo courtesy of Daniel Sánchez Ibarra (Wikimedia Commons).
Micro-World

Rainbow Mountain in Natural Diamond

An iridescent feather inclusion in natural diamond bears resemblance to Rainbow Mountain in Peru.
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Figure 2. Layers of limestone and chert plastically deformed and folded at high pressure and temperature during metamorphism. Photo by Dieter Mueller (dino1948)/licensed under CC BY SA 4.0.
Colored Stones Unearthed

Gems Formed in Metamorphic Rocks

Gemstones formed in metamorphic environments offer insights into the earth’s history and the evolution of tectonic activity that led to their formation.
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Figure 1. Greenland’s rubies are characterized by abundant twinning planes. The twinning planes are not altered by the treatment at a larger scale, but features associated with the twinning can be significantly affected by heating. Photo by S. Wongchacree; field of view 14.40 mm.
Gem News International

Characteristics of Treated Rubies from Greenland

An overview of the treatment process of ruby and pink sapphire from Greenland and its effect on inclusion scenes and chemistry.
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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