Our Gemstone Encyclopedia has information on over 300 gemstones, from traditional and popular jewelry standards to collector's stones that rarely appear for sale. Each entry has photos and detailed information about the gem's properties. Entries for jewelry stones also have price guidelines and discussions of their most important value factors.

Browse through our Gem Encyclopedia, search for a specific gem, or use our filters to find different types of gemstones.

What is a Gemstone?

Gemstones are minerals that have been chosen for their beauty and durability, then cut and polished for use as human adornment. Of course, there are exceptions to this definition. Pearls and amber are well-known gemstones but they're not minerals. They have organic origins. People frequently wear opals as jewelry stones, but these delicate gems require a great deal of care. Read this article to learn more.

Can Any Gem be Worn as Jewelry?

All gemstones have something appealing about them, whether that's their appearance, their symbolism, their rarity, or an unusual physical or optical property. However, not all gems make good jewelry stones. Some are just too fragile to wear. In the Gem Listings below, popular jewelry and collector's stones will have Wearability grades noted in their entries. These can range from "Excellent" to "Display Only." Read this article to learn more.

What are Precious and Semi-Precious Stones?

People have classified gems in many different ways. Traditionally, precious stones were the Big Four gemstones — diamonds, emeralds, rubies, and sapphires. Semi-precious stones were everything else. Today, gemologists don't use these terms because they imply that some gems are better or worth more than others. In fact, some so-called semi-precious stones would be worth far more than so-called precious stones. Read this article to learn more.

Are Lab-Created Gemstones Real Gemstones?

Lab-created or synthetic gemstones have the same optical and physical properties as their natural counterparts. They're grown from the same chemical ingredients and under the same physical conditions as mined gems, except at a greatly accelerated rate. Lab-created gems aren't fakes. For example, lab-created rubies are real rubies, but they're not natural rubies. (They're also far less expensive than their mined counterparts). Read this article to learn more.

Are Rare Gems More Valuable?

All gemstones are rare. Rough minerals with the right qualities for gem cutting make up a tiny percentage of mined material. However, some minerals form more rarely than others in nature, because they either require very specific conditions to form or contain elements that occur rarely on Earth. Nevertheless, that doesn't necessarily mean rare gems are more valuable. Consumer demand plays a critical role in a gem's value. Some rare gems are so little known there's just no market for them. Read this article to learn more.

How Can I Learn More About Gemstones?

The International Gem Society (IGS) offers several online courses for people interested in learning more about gemstones. If you're interested in starting a career in the world of gemstones, our Professional Gemologist Certification Course will give you the knowledge and skills you'll need. You'll learn the basics of gemology, the properties of gemstones, how to use essential gemology tools, and how to identify different gemstones.

If you're interested in learning about a specific type of gemstone, the IGS also offers mini-courses on a wide variety of popular gemstones, such as diamonds, rubies, sapphires, emeralds, pearls, and more. These are perfect for prospective gemstone buyers who want to learn more before making an expensive purchase.

If you're a novice gemologist who wants to learn more about gemology tools, or someone interested in investing in gemstones, the IGS has courses for you, too.

Check out our full List of Courses to learn more.

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Gemstone Encyclopedia