Pearl
There are many myths about pearls. The ancient Chinese believed pearls to be the tears of dragons. The ancient Greeks however, associated pearls with Aphrodite, the goddess of love while the Romans associated pearsl with their goddess Isis. The Indians believed pearls were drops of dew that fell in the sea. In Ceylon, it was believed that pearls were the tears of Adam and Eve. While the Polynesians believed that pearls were a gift of love to Princess Bora Bora from Oro, their god of fertility and peace.
In reality, pearls are produced in shellfish when a grain of sand or irritant gets into its soft flesh. The shellfish coats this irritant with layer after layer of nacre, which over the years becomes a precious pearl.
Pearls can be cultivated by slipping beads or grains into the oyster to force it to produce pearls over time. Pearls are cultivated in Japan and China. More now in China as the pollution of the waters in Japan is decreasing pearl production.
To choose a good pearl, look at its luster. The shinier and more intense reflections appear on the pearl's surface, the better the pearl.
For cultured pearls, the larger the pearl, the more expensive.
Spherical pearls are also the most valuable pearls.
As for choosing the color of the pearl, since pearls come in white, black, peach, pink, lilac and even gold (I saw gold pearls in China, but those were by far the most expensice), pick the color that you, or the one who will wear the pearls look best in.

Pearl Earrings: 18k White Gold Tahitian Cultured Pearl
Each earring holds a rare, black, Tahitian cultured pearl. Earrings are mounted on 18k white gold posts and have push backs for pierced ears.

Pearl Necklace: Sterling Silver Oval Cultured Pearl
Sterling silver infinity symbols are linked between sections of oval freshwater cultured pearls.