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TITLE: How Does a Crystal Become a Gem?


Skilled gem-cutters transform mineral crystals into sparkling gems. The exact procedure varies with the type of mineral and desired cut. This series of photographs shows how one aquamarine crystal was cut into gems.

[Photo: ]The rounded surface of a cabochon enhances opaque and translucent stones as well as optical effects such as stars and cat's eyes.

[Photo: ]The large, flat surface of a step cut allows abundant light to enter, bringing out the color of emeralds, rubies, and other intensely colored stones.

[Photo: ]The facets of a brilliant cut reflect light, which shows off diamonds and other fiery gems. Variations include marquise and pear shapes.




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This 426-carat aquamarine crystal was cut into 12 gems totaling 56.58 carats

 

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Start by cutting the crystal with a diamond saw.

 

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Shape the cut crystal using an abrasive wheel.

 

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Grind facets at precisely determined angles.

 

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Polish the gem by pressing it against a rotating wheel.

 

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Here are three of the gems. The largest is 18.18 carats.


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Smithsonian National Museum of Natural History Department of Mineral Sciences website Credits