Which gem is considered the most-prized chatoyant gem in the world?

Cat's-eye chrysoberyl is regarded as the most-prized chatoyant gem due to its remarkable and striking optical phenomenon known as chatoyancy, which means "cat's eye" in French. This effect occurs when light reflects off the surface of the stone, creating a narrow band of reflected light that resembles the slit-eyed appearance of a cat's eye.

The quality of chatoyancy in cat's-eye chrysoberyl can be attributed to its unique internal structure, which allows the light to interact with aligned inclusions or fibrous structures within the gem. Notably, the best specimens display a sharp, vivid band of light that moves across the surface as the stone is rotated.

In comparison, while emeralds, opals, and diamonds are highly valued and beautiful in their own right, they do not exhibit chatoyancy in the same way that cat's-eye chrysoberyl does. Emeralds are prized for their color and rarity, opals for their play-of-color, and diamonds for their brilliance and hardness, but none are classified specifically as chatoyant gems. This distinctive feature of cat's-eye chrysoberyl not only enhances its appeal among collectors and gem enthusiasts but also elevates its status as the premier example of chatoyancy