Alexandrite

Alexandrite is a rare, remarkable, color-change variety of the chrysoberyl mineral, along with its cousins yellowish transparent chrysoberyl and chatoyant or cat’s-eye chrysoberyl. Alexandrite’s rarity is a result of its chemical makeup; the unlikelihood of this rare element chromium being in the right place to combine with aluminum and beryllium under exactly the right conditions to create alexandrite is what makes it so rare and valuable.