Color: The color of pearls varies with the mollusk and its environment. It ranges from black to white, with the rose of Indian pearls esteemed most. Other colors are cream, gray, blue, yellow, lavender, green, and mauve. All occur in delicate shades. Cultured pearls are being produced in virtually every color of the rainbow.
Opal is given as a symbol of hope, happiness and truth.
Color: Opal is fundamentally colorless, but such material is rarely found. Disseminated impurities generally impart to opal various dull body colors that range from the yellows and reds derived from iron oxides to black from manganese oxides and organic carbon. The milkiness of many white and gray opals is attributable to an abundance of tiny gas-filled cavities in them.