An Introduction to Gemology

Gemstone luster describes how a gem’s surface looks when it reflects light. Learn the common terms gemologists use for this property and what can…

Even the most general definition of a gem has many exceptions. Learn what qualities have been used to identify gemstones both scientifically and…

Gemologists use several different gem classification methods. Learn how the most common systems work and what they cover as well as exceptions…

Learn the difference between allochromatic and idiochromatic gems and why some gem species can occur in many color varieties and others occur…

Mechanical gemstone cleaning has benefits and risks. Learn all about ultrasonic, steam, and boiling systems and how gems might react to them.…

Learn what gemstone dispersion means, what causes it, and how it relates to other optical effects.

Gem species are mineral species prized for their durability and beauty. Learn how chemical formulas and crystal structures define species and…

The March birthstone, aquamarine is a popular gem. Learn how aquamarines form, what they look like, and how they get their blue to blueish green…

Satisfying the human desire for symmetry, trapiche gems have a special allure. Learn what makes these rarities so unique in our introductory article.…

Identifying gemstone treatments is difficult even for experienced gemologists. Learn about the many different ways gem color and clarity are…

Learn the scientific definition of crystal used by gemologists and answer some basic questions about what is and is not a crystal.

What’s the difference between a reflectometer and a refractometer? If you’re interested in studying or buying gems, learn the facts here.…

Learn how gems absorb wavelengths of light and how gemologists use gemstone absorption spectra to identify gems. There’s more to color than…

Gemstone identification requires a good reference library and some basic gemology tools. Before you go shopping, learn more about what you’ll…

The spectroscope is one of gemology’s principal tools. Our basic spectroscope instructions will teach you how to operate and calibrate this…

A versatile gem and the famous January birthstone, garnet is a favorite among jewelers and consumers. Learn how garnets form and how they get their…

A little gemology goes a long way. Learn how to clean your gemstone jewelry safely and how to deal with difficult jewelry settings and sensitive…

Quartz is one of the most abundant minerals on earth. Learn how quartz forms and how its most popular varieties get their colors.

Topaz requires specific and unusual conditions to form. Learn how topaz develops and how it gets its colors, from yellow and blue to rare and valuable…

Tourmalines are a large mineral group with a variety of chemical compositions. Learn how tourmalines form and why so many colors can appear in one…

Learn how lab grown sapphires are made and how gemologists can distinguish natural from synthetic sapphires.

How do emeralds form? Learn how the emerald growth process works and why it makes these gems rare, green, and very fragile.

How do gemologists distinguish between rubies and pink sapphires? Learn about the chemistry of corundum and the history of the color pink.

The geological conditions in which rubies and sapphires form are rare and extreme. Learn how these popular gems develop and how they get their colors.…

Not all pearls are perfectly round and white. Learn about keshi pearls and soufflé pearls, two beautiful byproducts of the cultured pearl industry.…

With dark bodies and colorful sheens, beautiful Tahitian pearls have mesmerized jewelry lovers for decades. Learn more about these and other…

With thick nacre and large sizes, South Sea pearls really stand out when compared to other pearl types. Learn more about these white and golden pearls.…

As consumers compare price and quality, freshwater cultured pearls are rapidly becoming more popular than Akoyas. Learn more about these amazing…

Since the beginning of the cultured pearl industry, Akoya pearls have ruled the market. Learn more about the quintessential round, white pearl.…

Do pearls form around grains of sand trapped in oysters? Learn the facts about pearl formation and the various mollusks that create these organic…

Many consumers don’t understand the difference between natural pearls and cultured pearls. Learn what these terms mean and how to distinguish…

Why are some gems so rare in nature? Learn which elements in the Earth’s crust are the rarest and how these ingredients help form uncommon gemstones.…

IGS member Richard Edley shares his experiences discovering California turquoise and offers advice on desert prospecting.

Curious about how opals form and show such stunning colors? Learn about the scientific theories behind opal formation and why some opals show a…

Thinking of becoming a gemologist? Consider these gemology career options, compare their estimated salaries, and decide which one may be right…

Learn what gemologists do in our introduction to gemology. Whether your interest is casual or professional, the world of gems will amaze you.

Gemstone transparency describes how much light passes through a gem and how it scatters. Learn what causes a gem to be opaque, translucent, or transparent.…

Gem formation usually involves mineral crystallization and other geological processes. Learn how these affect the gemstone properties gemologists…

Learn how diamonds formed geologically and how they became the virtual standard for engagement ring stones in this brief history of diamonds.…

Opals and pearls have special setting, cleaning, and storage needs. Our opal and pearl care guide will help you keep your jewelry beautiful.

Visit one of the top gem hunting spots in the US. Go alone or with the family. A gemology-themed vacation can be fun, educational, and (maybe) profitable.…

Gemstone birefringence is a measure of a gem’s double refraction. Learn how it’s used to identify gems and see the effects birefringent gems…

Gem identification is part detective work, part art. Learn how gemologists can distinguish gem species and determine whether a stone is natural…

We live in a world of crystals. You don’t have to dig deep into the Earth to find them. Even the bones in our bodies and the dust in the air contain them.…

Diamond is the hardest natural material in the world. However, it’s also brittle. Scientifically speaking, gemstone hardness measures the…

Rounds dominate the gem market, but fancy gem cuts offer many beautiful options. Learn about the most popular fancy shapes, such as heart and emerald…

Gem cutting styles refer to the shape and arrangement of facets. The three most basic styles are brilliant, step, and mixed. Learn what characterizes…

Not only do gemstone facets create beautiful patterns on gem surfaces, they also help gems shine. While gem cutters will learn all about facets,…

Lapidary is the art of working in stone. The term usually refers to the creation of small objects from gem materials. Read on to learn about the four…

Gemstone inclusions are materials trapped inside gems as they form. Learn how gemologists use inclusions to help identify gemstones and their…

Although many gem enthusiasts want to become collectors, they may not know where to begin. Read this article for tips on how to start a gem collection.…

How well do you know your birthstone gemology? Take our short quiz and learn about the composition, cutting, and value of birthstones.

Our gemstone care guide covers many popular gems. Learn how best to maintain your gemstone jewelry and what kinds of stresses and cleaning methods…

Gemological formulas identify the chemical composition of gems and minerals. Learn what the symbols, numbers, and parentheses mean.

Gemologists sometimes measure gemstone density or specific gravity to help with gem identification. Learn the basics of this property and how…

Your prized gemstones deserve custom faceting. Learn the benefits of working with precision faceters and tips for starting your own jewelry project.…

The faceting process turns rough stones into finished gems. Learn the steps custom faceters take to create unique gemstones that tell a client’s…

Today’s custom gem cutters use faceting equipment for precision work and design inspiration. Take a look at the toolkit of the new lapidary renaissance.…

In the gem design stage of jewelry making, faceters evaluate a stone’s qualities. Learn how to choose a cut for a gemstone as unique as your personal…

A precision faceter can turn a rough stone into a story gemstone as unique as each client. Choosing the right rough is the first step in the design…

Crystals have habits. In crystallography, mineral habits refer to the way crystals form within a specific mineral. There are six crystal systems.…

What does it take to become a professional gemologist? Try these sample gemology questions from the International Gem Society certification…

Learn what factors most influence a sphalerite appraisal and what kind of jewelry will best showcase this beautiful gemstone.

Should you wear chrysoprase jewelry only at night to protect the gem’s striking green color? Learn the facts here.

Opal jewelry is lovely, but aren’t these gems prone to scratching and breaking? Learn the best ways to wear these colorful but delicate stones.…

Learn about the different crystal growth methods used to artificially create gemstones in laboratories.

Learn about synthetic diamond creation and the challenges buyers face determining whether a diamond is natural or artificial.

Australian opals account for 95% of the world’s supply. Learn about Australia’s geological history, the start of its opal trade, and its sources.…

Many varieties of gems besides diamond can be created in the laboratory. Our synthetic gemstone guide covers many examples and explains their…

Learn how to organize your gemstone collection. Choose the storage and display options that are right for you and create a practical cataloging…

Are you a hobbyist or professional gemologist facing high equipment costs? Read our IGS series of articles that can help you build your own gemology…

Tech advances and market forces make it essential for gem buyers to know the science behind synthetic gemstones and gem formation. Learn the basics…