Chatoyancy is a lustrous, cat's eye effect seen in some gemstones and minerals.
In a chatoyant material, light is reflected in thin bands within the mineral or stone. Chatoyancy arises either from the fibrous structure of a material, or from fibrous inclusions or cavities within the stone.
Chatoyant gemstone material is cut into cabochons for the best display of this stunning optical phenomenon. The best way to describe it is a sharply defined band of light that moves across the stone when it is rotated.
The name comes from the French word chatoyer meaning "cat's eye," because it resembles the slit eye of a cat.
An iridescent or labradorescent object displays many lustrous, changing colors.
Iridescence and labradorescence are caused by dispersion of light in cracks and flaws resulting in a rainbow-like play of color (as often seen in an oil slick or a soap bubble). The colors tend to change as the angle of view changes.
The word Iridescent comes from the Greek word iris, which means "rainbow".
Sometimes you may need the stone under a bright light to see the full effect. Rainbow Obsidian is a one example of this. Rainbow Obsidian and both Gold or Silver Sheen Obsidian. Please see Obsidians under Gemstones Types for more information on these beautiful materials!
For more information on other semi precious gemstones that display these optical phenomenons, please click on the name to your right. If you don't see the specific stone you can enter it in the search box above and the click the News and Information tab to see if there is an informative page available.