October 2024 Birthstone

Opal: The Gem Containing Galaxies

October Birthstone

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SU24 G&G Issue Cover

Lab-Grown Diamonds, Chinese Cassiterite, and a Tourmaline Inclusions Chart

New Gems & Gemology Issue

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featured

Research & News

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. This 10.02 ct E-color, VS1-clarity emerald-cut diamond is an example of the great strides made in HPHT growth technology in the past two decades, as laboratory-grown diamonds have become an important sector of the gem diamond market. Photo by Johnny Leung. The as-grown CVD diamond plate (1.24 ct, 8.41 × 8.60 × 1.26 mm) was manufactured by GIA at its New Jersey research facility. Photo by Adrian Chan.
Feature

Laboratory-Grown Diamonds: An Update on Identification and Products Evaluated at GIA

Reviews the advancements and major trends in laboratory-grown diamonds observed by GIA since 2007.
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Figure 1. The multicolored pearl weighing 90.08 ct and measuring 28.66 × 22.19 × 18.50 mm. Photo by Gaurav Bera.
Lab Notes

A Large Multicolored Natural Blister Pearl

A large baroque-shaped blister pearl with a unique multicolored appearance is examined in the Mumbai laboratory.
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Figure 1. This unheated 11.43 ct purplish red round ruby cabochon displayed a white twelve-rayed double-star phenomenon. Photo by Nuttapol Kitdee.
Micro-World

Fireworks in Ruby

An unheated purplish red ruby cabochon displays a white twelve-rayed double-star phenomenon.
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Figure 1. Synthetic alexandrite, amethyst, beryl, corundum, diamond, and fire opal. The three smallest stones are synthetic diamonds ranging from 0.06 to 0.14 ct. Photo by Robert Weldon.
Colored Stones Unearthed

Laboratory Growth of Gem Materials and the Attempt to Replicate Nature

Provides an overview of processes for synthesizing gem materials and explains how unique growth conditions enable them to be separated from naturally formed gems.
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Figure 1. Emeralds in matrix and various cut stones from the Curlew mine in Western Australia. All stones were mined in 2023. The cut stones are untreated and range from 0.45 to 7.92 ct (triangular shape). Photo by Lhapsin Nillapat; courtesy of Matthew Allen (The Gemstone Trading Company).
Gem News International

New Emerald Production from the Curlew Mine, Western Australia

GIA’s Bangkok laboratory studies emeralds from the Curlew mine’s recently renewed production.
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Left: A sci-fi scene in this oval measuring 48 × 72 × 8 mm and weighing 247 ct depicts streaks of light filtering through pine forests and reflecting in the lakes below. At the horizon, a giant moon emerges from behind the mountains. Photo by Robert Weldon. Right: Detail of variations in the perceived color, depending on the orientation of the light source. Photomicrograph by Nathan Renfro.
In the Spotlight

Dance of Light and Color: Painted Labradorite

Artist Valentina Fetisova transforms labradorite cabochons into remarkable works of art.
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This collection of 50 tourmalines showcases the gem’s wide-ranging color palette. Photo by Robert Weldon; courtesy of Bruce A. Fry.
Chart

Micro-Features of Tourmaline

Provides a visual guide to the internal features of tourmaline as well as tourmaline inclusions in other gem hosts.
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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