Some people use the term "black pearl" to refer to any dark colored pearl, dyed or natural color. Black pearls are not necessarily black. More often than not they range from a light to very dark gray, but they may also look green, pink, lavender, blue or brown. It's the oyster source, not color, that determines if pearls are called black pearls. "Black pearl" is a generic term that refers to pearls from:
• Black-lipped pearl oysters (Pinctada margaritifera), Western to Central Pacific & Indian Oceans.
• La Paz pearl oysters (Pinctada mazatlanica), Eastern Pacific between Baja California & Peru.
• Rainbow-lipped (western-winged) pearl oysters (Pteria sterna), Eastern Pacific between Baja California & Peru.