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Diamond is the hardest natural substance known to man — and the only gem that consists of a single element. Diamonds began forming over three billion years ago as pure carbon crystals buried 100 miles beneath the earth’s surface. Under the force of intense heat and pressure, these crystals hardened and became embedded in kimberlite, a form of igneous rock. Diamonds are very rare; over 250 tons of kimberlite ore must be mined and processed to produce a 1-carat gemstone.
In some cases, erosion in the kimberlite caused diamonds to be released from the ore. This resulted in a secondary deposit called “alluvial” diamonds. These diamonds flow toward the sea and settle in riverbeds, often far from their original source.
When diamonds are mined, they look like clear or colored crystal rocks and are referred to as “rough.” Diamonds were first mined in India over 3,000 years ago. Today, Africa, Australia, Russia, Brazil, and Canada are sources of commercial deposits of diamonds.
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