Explore the amazing world of gems — how they form, where they come from, and the stories behind the world's most famous stones.
Diamond scores 10 on the Mohs hardness scale — nothing can scratch it except another diamond. They form about 100 miles underground and take over a billion years to create!
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A tiny amount of chromium — the same element that makes traffic lights red — gives rubies their beautiful color. The finest rubies come from Burma and are called "pigeon blood" rubies.
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While blue sapphires are most famous, sapphires come in pink, yellow, orange, green, and purple. They're all the same mineral — corundum — just with different trace elements.
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Emeralds form when hot fluids carry beryllium and chromium through cracks in ancient rocks. They grow so slowly that most large emeralds have tiny natural fractures called "jardin" — which means garden in French!
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One of the world's rarest gems, alexandrite appears green in daylight and red under incandescent light. It was discovered in Russia's Ural mountains in the 1830s.
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Star sapphires and star rubies show a six-pointed star that glides across the stone in light. This optical effect is called asterism, caused by tiny needle-like inclusions inside the stone.
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45.52 carats
Deep Blue
One of the most famous gemstones in the world, now at the Smithsonian Museum. Its blue color comes from boron atoms inside the crystal.
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24.78 carats
Fancy Pink
Sold at auction for $46 million in 2010. Pink diamonds are so rare that most gemologists will never see one in their career.
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25.59 carats
Pigeon Blood Red
The world's most valuable colored gemstone per carat. Burmese rubies of this quality are described as the color of a "pigeon's blood" — a vivid, pure red.
Want to learn more about gemstones?
Gemstone Fundamentals →