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June Birthstone

Pearl, Moonstone, Alexandrite: Gems of Phenomenal Beauty

June Birthstone

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SP25 GG Issue Cover

FTIR Peaks in Corundum, Winston Red Diamond, and Catherine de' Medici's Pendant

New Gems & Gemology Issue

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featured

Research & News

Figure 6. This selection of deep-UV fluorescence images of natural diamonds highlights the wide range of potential emission patterns and colors that can be observed, evidence of diamond’s unique growth and residence history. E: Most natural type II diamonds show blue fluorescence with mosaic-like polygonized dislocation patterns, differing from characteristic type II CVD- or HPHT-grown diamond patterns (compare with figures 8–10). Images by Garrett Koneval (A), Najmeh Anjomani (B), Wuyi Wang (C), Christopher Vendrell (D), Ulrika F.S. D’Haenens-Johansson (E), and Sandeep Kabariya (F).
Glowing Gems - What Does Fluorescence Tell Us?

G&G in a Flash: What Does Fluorescence Tell Us?

Learn about the principles, mechanisms, and characteristics of luminescence that create the impressive and memorable glow of gemstones.
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CVD diamond plate and HPHT laboratory grown diamond
Laboratory-Grown Diamonds Update

The Latest on Laboratory-Grown Diamonds

Learn the latest trends by GIA on the laboratory-grown diamond industry.
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Hand holding demantoid garnet rough in matrix.
Field Gemology Update

The Latest in Field Gemology from Wim Vertriest

Learn the latest on Madagascar sapphires and demantoid garnets from Wim Vertriest, GIA Manager of Field Gemology.
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Figure 1. A set of 35 non-nacreous pearls submitted for examination exhibited a variety of colors and surface structures, indicating they were formed by various mollusk species. Photo by Nuttapol Kitdee.
Lab Notes

Natural Non-Nacreous Pearls from Various Marine Mollusks

The Bangkok laboratory studies 35 loose non-nacreous pearls from a wide range of marine mollusk species.
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Prismatic elongated zircon in Kashmir sapphire. Photomicrograph by Narint Jaisanit; field of view 2.88 mm.
Micro-World

Prismatic Zircon in Kashmir Sapphire

Elongated zircon inclusions display attractive birefringent interference colors in a blue sapphire from Kashmir.
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Figure 1. 18K yellow gold “Flames” ring with 25.19 ct Mexican fire opal. Courtesy of Paula Crevoshay.
Gem News International

Tucson 2025 Overview

A summary of the findings at the 2025 Tucson gem shows.
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Figure 1. The 2.33 ct Winston Red diamond, displaying a vibrant Fancy red color. The old mine brilliant-cut stone measures approximately 8 mm in diameter. Photo by Robert Weldon; courtesy of Ronald Winston.
Feature

A Study of the Winston Red: The Smithsonian’s New Fancy Red Diamond

Presents the first scientific and historical study conducted on the 2.33 ct Winston Red, the fifth-largest known Fancy red diamond in existence.
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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