The mineral or gemstone chrysoberyl, not to be confused with beryl, is an aluminate of beryllium with the formula BeAl2O4. The name chrysoberyl is derived from the Greek words chrysos and beryllos, meaning "a gold-white spar". Despite the similarity of their names, chrysoberyl and beryl are two completely different gemstones.

Chrysoberyl is the third-hardest natural gemstone and lies between corundum and topaz on the hardness scale. An interesting feature of its crystals are the cyclic twins called trillings. These twinned crystals have a hexagonal appearance, but are the result of a triplet of twins with each "twin" taking up 120 degrees of the cyclic trilling.

There are three main varieties of chrysoberyl: ordinary yellow chrysoberyl, cat's eye or cymophane, and alexandrite. Although yellow chrysoberyl was referred to as chrysolite during the Victorian and Edwardian eras, that name is no longer used in the gemological nomenclature. Ordinary chrysoberyl is a yellowish-green, transparent to translucent chrysoberyl and has often been referred to in the literature as chrysolite due to the common olive color of many of its gems, but that name is no longer used in the gemological nomenclature.

When the mineral exhibits good pale green to yellow color and is transparent, then it is used as a gemstone.

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