The chameleon-like variety of chrysoberyl, alexandrite, is one of the most valuable and rare coloured gemstones. It was discovered in the 1830s in the Ural Mountains of Russia and subsequently named after Czar Alexander II, heir to the throne at the time. The find was celebrated as the colours of this extraordinary gemstone matched the national military colours of Imperial Russia.
Known as ‘emerald by day, ruby by night,’ alexandrite is green in daylight, and changes to red in incandescent light. This colour change effect is what makes this gemstone one of the most valuable and sought-after. Rarer still is an alexandrite gemstone exhibiting a cat’s eye effect.
The deposits from the Ural Mountains have now depleted. However, alexandrite has been found in Sri Lanka, Zimbabwe and Brazil.