Pearl
Pearls were precious to many cultures, past and present, throughout the world. Pearl was among the favorite gem materials of the Roman Empire. In England, the Tudor period in the 1500s was known as "the pearl age".
On his third voyage to the Americas, Columbus kept his discovery of pearls in the New World a secret, and he fell out of favor with the King of Spain. In the Orient, pearl powders are sold as an aphrodisiac. For medicinal use, pearls are composed of calcium carbonate, an essential supplement for promoting strong bones and teeth, as well as the prime ingredient in stomach antacids.
Pearls are unique in that they are the only gem of the sea, and one of the only gems to be created by living creatures (the other is amber). They are also special in that they require no faceting or polishing to reveal their natural beauty.
In the early 1900s, the first successful commercial culturing of round pearls began, and since the 1920s cultured pearls have almost completely replaced natural pearls in the market.