Chrysoberyl
Chrysoberyl is an amazing gem mineral that gives us two of the most magnificent gemstones - colour-change alexandrite and cat's eye chrysoberyl.
Alexandrite can display an impressive colour change (metamerism) from emerald green in daylight to raspberry red under incandescent light. It is coloured by traces of chromium.
Cat's eye chrysoberyl (also known as cymophane) is found in a variety of colours, including green, brown, yellow and golden, with the last two colours being especially desirable.
One of chrysoberyl's great properties is its excellent hardness (resistance to scratching). With a rating of 8.5 on the Mohs scale, it is the third hardest natural gem material (just below ruby and sapphire and slightly harder than topaz). This means chrysoberyl is ideal for any type of jewellery.
Chrysoberyl also has a high refractive index, so it displays a fantastic brilliance. That means even the normal examples of this gemstone (without colour change or cat's eye) can be very beautiful, as well as much more affordable than their more exotic relatives.
The mineral itself is an aluminium beryllium oxide and belongs to the orthorhombic crystal system. Despite the name, chrysoberyl is not related to the beryl family (which includes emerald, aquamarine and morganite) and has a different composition.
The name chrysoberyl is derived from the Greek words chrysos and beryllos, meaning "a gold-white spar".
Chrysoberyl is found in many countries, including Brazil, Myanmar, Tanzania, Madagascar and Sri Lanka.
Cat's eye chrysoberyl cabochon from Sri Lanka