Density: 3.7 / Hardness: 8.5 / Varieties: Chrysoberyl, Alexandrite, Cat’s eye.
Short prisms with diamond section, almost always stained. Single macle made up of two individuals oriented at 60° to each other, or multiple, in a six-pointed star shape.
Chrysoberyl is transparent to translucent, yellowish green to brownish, sometimes bluish. Vitreous luster, sometimes with a shimmering effect.
Alexandrite is a dark green chrysoberyl that turns purplish-red under artificial light. The variety that shows the shimmering effect is called cat’s eye.
They are found in pegmatites and some metamorphic rocks.
It was in the Urals that a chromium-rich chrysoberyl was discovered around 1830, whose colour changes according to the lighting used. It was named Alexandrite in honour of Tsar Alexander II.
The shimmering effect is due to microscopic alignments of channels within the mineral. To highlight this effect, chrysoberyl is cut into cabochons.