An Introduction to Gemology
The basic building blocks of understanding the science of gemstones.
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How to Start a Gem Collection
Although many gem enthusiasts want to become collectors, they may not know where to begin. Read this article for tips...
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Understanding Gemological Formulas
Gemological formulas identify the chemical composition of gems and minerals. Learn what the symbols, numbers, and parentheses mean.
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What is Gemstone Luster?
Gemstone luster describes how a gem's surface looks when it reflects light. Learn the common terms gemologists use for this...
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What is a Gem?
Even the most general definition of a gem has many exceptions. Learn what qualities have been used to identify gemstones...
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A Guide to Gem Classification
Gemologists use several different gem classification methods. Learn how the most common systems work and what they cover as well...
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What are Allochromatic and Idiochromatic Gems?
Learn the difference between allochromatic and idiochromatic gems and why some gem species can occur in many color varieties and...
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Mechanical Gemstone Cleaning
Mechanical gemstone cleaning has benefits and risks. Learn all about ultrasonic, steam, and boiling systems and how gems might react...
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What is Gemstone Dispersion?
Learn what gemstone dispersion means, what causes it, and how it relates to other optical effects.
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What are Gem Species and Gem Varieties?
Gem species are mineral species prized for their durability and beauty. Learn how chemical formulas and crystal structures define species...
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How Do Aquamarines Form?
The March birthstone, aquamarine is a popular gem. Learn how aquamarines form, what they look like, and how they get...
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Trapiche Gems: An Introduction
Satisfying the human desire for symmetry, trapiche gems have a special allure. Learn what makes these rarities so unique in...
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Understanding Gem Synthetics, Treatments, and Imitations, Part 5: Gemstone Treatments
Identifying gemstone treatments is difficult even for experienced gemologists. Learn about the many different ways gem color and clarity are...
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What is a Crystal?
Learn the scientific definition of crystal used by gemologists and answer some basic questions about what is and is not...
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What is a Gem Reflectometer?
What’s the difference between a reflectometer and a refractometer? If you’re interested in studying or buying gems, learn the facts...
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What are Gemstone Absorption Spectra?
Learn how gems absorb wavelengths of light and how gemologists use gemstone absorption spectra to identify gems. There’s more to...
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Recommended Gemology Tools and Instruments
Gemstone identification requires a good reference library and some basic gemology tools. Before you go shopping, learn more about what...
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Spectroscope Instructions for Novice Gemologists
The spectroscope is one of gemology’s principal tools. Our basic spectroscope instructions will teach you how to operate and calibrate...
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How Do Garnets Form?
A versatile gem and the famous January birthstone, garnet is a favorite among jewelers and consumers. Learn how garnets form...
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How to Clean Your Gemstone Jewelry
A little gemology goes a long way. Learn how to clean your gemstone jewelry safely and how to deal with...
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How Does Quartz Form?
Quartz is one of the most abundant minerals on earth. Learn how quartz forms and how its most popular varieties...
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How Does Topaz Form?
Topaz requires specific and unusual conditions to form. Learn how topaz develops and how it gets its colors, from yellow...
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How Do Tourmalines Form?
Tourmalines are a large mineral group with a variety of chemical compositions. Learn how tourmalines form and why so many...
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What are Lab-Grown Sapphires?
Learn how lab grown sapphires are made and how gemologists can distinguish natural from synthetic sapphires.
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How Do Emeralds Form?
How do emeralds form? Learn how the emerald growth process works and why it makes these gems rare, green, and...
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What’s the Difference Between Rubies and Pink Sapphires?
How do gemologists distinguish between rubies and pink sapphires? Learn about the chemistry of corundum and the history of the...
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How Do Rubies and Sapphires Form?
The geological conditions in which rubies and sapphires form are rare and extreme. Learn how these popular gems develop and...
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Keshi Pearls and Soufflé Pearls
Not all pearls are perfectly round and white. Learn about keshi pearls and soufflé pearls, two beautiful byproducts of the...
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Tahitian Pearls: Beautiful Black Pearls
With dark bodies and colorful sheens, beautiful Tahitian pearls have mesmerized jewelry lovers for decades. Learn more about these and...
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South Sea Pearls: the Complete Guide
With thick nacre and large sizes, South Sea pearls really stand out when compared to other pearl types. Learn more...
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Freshwater Cultured Pearls
As consumers compare price and quality, freshwater cultured pearls are rapidly becoming more popular than Akoyas. Learn more about these...
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Akoya Pearls: the Complete Guide
Since the beginning of the cultured pearl industry, Akoya pearls have ruled the market. Learn more about the quintessential round,...
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How Do Pearls Form?
Do pearls form around grains of sand trapped in oysters? Learn the facts about pearl formation and the various mollusks...
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Natural Pearls vs Cultured Pearls
Many consumers don’t understand the difference between natural pearls and cultured pearls. Learn what these terms mean and how to...
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Uncommon Elements Make Uncommon Gemstones
Why are some gems so rare in nature? Learn which elements in the Earth’s crust are the rarest and how...
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Desert Prospecting: Discovering California Turquoise
IGS member Richard Edley shares his experiences discovering California turquoise and offers advice on desert prospecting.
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How Do Opals Form?
Curious about how opals form and show such stunning colors? Learn about the scientific theories behind opal formation and why...
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Gemology Career Options
Thinking of becoming a gemologist? Consider these gemology career options, compare their estimated salaries, and decide which one may be...
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An Introduction to Gemology
Learn what gemologists do in our introduction to gemology. Whether your interest is casual or professional, the world of gems...
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What is Gemstone Transparency?
Gemstone transparency describes how much light passes through a gem and how it scatters. Learn what causes a gem to...
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Gem Formation: How are Gemstones Created?
Gem formation usually involves mineral crystallization and other geological processes. Learn how these affect the gemstone properties gemologists study.
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A Brief History of Diamonds
Learn how diamonds formed geologically and how they became the virtual standard for engagement ring stones in this brief history...
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Opal and Pearl Care Guide
Opals and pearls have special setting, cleaning, and storage needs. Our opal and pearl care guide will help you keep...
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Top Spots for Gem Hunting in the US
Visit one of the top gem hunting spots in the US. Go alone or with the family. A gemology-themed vacation...
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What is Gemstone Birefringence?
Gemstone birefringence is a measure of a gem's double refraction. Learn how it’s used to identify gems and see the...
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An Introduction to Gem Identification
Gem identification is part detective work, part art. Learn how gemologists can distinguish gem species and determine whether a stone...
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A World of Crystals
We live in a world of crystals. You don’t have to dig deep into the Earth to find them. Even...
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Gemstone Hardness and Wearability
Diamond is the hardest natural material in the world. However, it’s also brittle. Scientifically speaking, gemstone hardness measures the ability...
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