Jewelers will be familiar with the word “chatoyant.” It comes from the French verb “chatoyer,” meaning “to shimmer,” and when the adjective is referring to a gemstone, it describes a band of light that shines from inclusions in the stone. It specifically occurs when a stone is cut in the “en cabochon” form. The adjective can also be used outside of a gemstone context — in that case, “chatoyant” describes anything with a changing, shimmering luster, such as a fabric that changes in different lighting.