Alexandrite is a rare variety of the mineral chrysoberyl, and its name is derived from Alexander II of Russia, who was born on the day that the first Alexandrite specimen was found. Alexandrite exhibits a remarkable optical phenomenon known as chatoyancy, or 'cat's eye', which results in a band of light that appears to move across the surface of the stone as it is rotated. Alexandrite is also notable for its ability to change color in different lighting conditions. In natural sunlight, Alexandrite typically appears green, but it will take on a reddish hue when exposed to artificial light. This color-changing ability makes Alexandrite a popular choice for jewelry, and it is often used in rings, earrings, necklaces, and pendants. Although Alexandrite is found in several countries around the world, the finest specimens come from Sri Lanka and Brazil.