1. A luminous optical effect in certain gemstones and minerals that resembles the eye of a cat, caused by the reflection of light from parallel fibers or inclusions within the stone.
Usage: gemology term; also called cat's eye effect

Examples

• The chatoyancy of the tiger's eye stone made it appear to glow with an inner light.
• Gemologists value chatoyancy as a distinctive feature that increases the appeal of certain stones.
• The chrysoberyl exhibited a striking chatoyancy when turned under the jeweler's lamp.
• Chatoyancy is most commonly observed in cat's eye quartz and other fibrous minerals.
• The stone's chatoyancy shifted as she rotated it, creating a mesmerizing effect.