Chrysoberyl is an aluminate of beryllium. Although it contains beryllium, it should not be confused with a different variety of gemstones which also contains beryllium, known as beryl. Unlike beryl, chrysoberyl is harder, with a rating of 8.5 on the Mohs hardness scale.
Confusingly, chrysoberyl was referred to as chrysolite in the 17-18th centuries. This name was also used to refer to olivine or peridot due to their similar pale green colour. Yet, chrysolite is rarely used today.
There are three main varieties of chrysoberyl gemstones used in jewellery: ordinary chrysoberyl, cymophane (cat’s eye) and alexandrite. Ordinary chrysoberyl can vary in colour from a slight yellow-green tint to a stronger citrus colour or deep muddy glow. Chrysoberyl was popular in 18th century Spanish and Georgian Era jewellery, particularly small rose cut stones set like mosaics in elaborate chandelier earrings. Cymophane known as cat’s eye, is usually cloudier and cut in cabochons to show off the distinctive silky inclusions that form a striking cat’s eye effect across the centre of the stone. Alexandrite, was named after the last Tsar of Russia, Alexander II, as according to legend the first deposit was discovered in the Ural mountains on the monarch’s birthday.