Rainbow moonstone has a patchy, milky appearance, which comes from the white orthoclase layers and inclusions. When the stone catches the light, the reflection off the layers and inclusions produces a rainbow effect. The colour play has made this a very popular stone with buyers and it frequently appears in silver jewelry. Unfortunately, there is a great deal of poor-quality material on the market that has virtually no colour play and is full of cracks and chips, so one has to look pretty hard for good examples.