Discovered in the Ural Mountains in the 1830s, alexandrite is one of the rarest varieties of chrysoberyl. Its famous colour change — green in daylight, red to purple under incandescent light — is caused by traces of chromium.
Judging the change
Reports describe the change as strong, moderate or slight. A strong, clean change between two saturated colours is the most valuable.
Size matters
Fine alexandrite above one carat is exceptionally rare, which is why even small stones with a good change command high prices per carat.
Care
With a hardness of 8.5, alexandrite is durable enough for everyday rings.
