The name chrysoberyl comes from the Greek and means “gold-colored honey”, although it comes in shades of lemon yellow, greenish yellow, golden colors and shades of mint green to brownish green. (When found in the mint greenish blue color, it is considered the most expensive.) It’s name also comes from the French word “chat” meaning cat and “oeil” meaning eye. Chrysoberyl is known for its streak of light result known as the cat’s eye effect. It was discovered in 1789 by the then famous geologist Abraham Gottlob Werner.
The cat’s eye effect is called “chatoyancy” in technical terms. Needle like inclusions cause the chatoyancy which looks like the opening and closing of a cat’s eye, a perpendicular line as the stone is rotated. The cabochon cut shows off the cat’s eye effect. When the cat’s eye effect does not show in the stone it will be faceted.
Although beryl is in its name, chrysoberyl it is not part of the beryl family. Chrysoberyl is considered a color changing stone. Alexandrite is also a color changing stone and is part of the chrysoberyl family. When this color changing stone changes from emerald green in daylight to a purple red in incandescent light, it is called alexandrite. The change in color needs to be medium to strong to be called an alexandrite. It is called chrysoberyl when the color change is faint. Alexandrite has a more distinct change in color. Chrysoberyl is considered a gemstone when the stone shows a “good pale green to yellow color and is transparent”.
Chrysoberyl is an 8 ½ out of 10 on the Mohs scale of hardness. Only sapphire and diamond are harder. It is known for its toughness and durability.