The birth of a pearl is truly a miraculous event. Unlike gemstones or precious metals that must be mined from the earth, pearls are grown by live oysters far below the surface of the sea. They are born from oysters complete -- with a shimmering iridescence, lustre and soft inner glow unlike any other gem on earth. A natural pearl begins its life as a foreign object, such as a parasite or piece of shell that accidentally lodges itself in an oyster's soft inner body where it cannot be expelled. To ease this irritant, the oyster's body takes defensive action. The oyster begins to secrete a smooth, hard crystalline substance around the irritant in order to protect itself. This substance is called "nacre." As long as the irritant remains within its body, the oyster will continue to secrete nacre around it, layer upon layer. Over time, the irritant will be completely encased by the silky crystalline coatings. And the result, ultimately, is the lovely and lustrous gem called a pearl. How something so wondrous emerges from an oyster's way of protecting itself is one of nature's loveliest surprises. For the nacre is not just a soothing substance. It is composed of microscopic crystals of calcium carbonate, aligned perfectly with one another, so that light passing along the axis of one crystal is reflected and refracted by another to produce a rainbow of light and color.

When it starts out, a pearl isn't very pretty. At first, it's just a tiny piece of sand -- or rock -- or maybe even the body of a bug--that gets stuck inside an oyster's shell.

The oyster coats the baby pearl with a smooth layer of minerals. As the oyster keeps adding more layers, the pearl grows bigger and becomes more rounded.

Old stories from India say that pearls are dewdrops from heaven that fell into the sea. Indian warriors were said to encrust their swords with pearls as a reminder that swords create tears and sorrow.

Cultured pearls are made by mollusks with human intervention; an irritant introduced into their shells causes a pearl to grow. Real pearls that are not cultured are fairly rare and extremely vaulable. A 16 inch strand of white South Sea pearls retails for $40,000 to $50,000. The world record for the highest price paid for a cultured pearl necklace was $2.3 million at Sotheby's in 1992.

Interestingly, the best cultured pearls are those that come from an oyster that dies after the pearl is removed. Oysters that do not die after the pearl has been extracted produce what are referred to as "Biwa" pearls. Generally but not always, Biwa pearls fetch a lower price than the impending death variety.