Pearls are characterized by their translucence and luster and by a delicate play of surface color called orient. The colour of pearls varies with the mollusk and its environment, ranging from black to white. Other colours are cream, gray, blue, yellow, lavender, green, and mauve. All occur in delicate shades. The surface of a pearl is rough to the touch.
Pearls come in a wide range of sizes.
The largest naturally occurring pearls are the baroque pearls. Its colour varies from deep red to pale rose red, in some cases with a tinge of purple. The most valued is a pigeon blood red. Ruby is a mineral of very limited distribution. The name used in mineralogy is Olivine, because of its olive green colour.