Like all precious gemstones, pearls are rare and quite valuable. However, in contrast to natural diamonds, natural pearls are very hard to come by. Most pearls used today, even in the most expensive jewelry pieces, are not natural pearls, but rather, cultured pearls.
Natural pearls are pearls found in the wild, without any human involvement. Once, such pearls were found in all parts of the world, but today they are extremely scarce and are only discovered in the seas of Bahrain. Natural pearls are almost 100% calcium carbonate and conchiolin. Pearls are actually created accidentally, when a parasite enters the mollusk and triggers a protective response causing a secretion of calcium carbonate and conchiolin to cover the intruder. The result is a remarkably beautiful and sturdy pearl.
Since natural pearls are so difficult to find these days, ways of replicating the pearl-making process have been created. Pearls created through these procedures have become known as cultured pearls. Essentially, cultured pearls are the shell’s response to a tissue implant. A very small piece of mantle tissue from a donor shell is placed into a recipient shell where a pearl sack will form. The tissue then triggers calcium carbonate into the pocket. There are several ways of growing cultured pearls. Both freshwater and saltwater shells can be used, the graft can be transplanted into the mantle or into the gonad, and a spherical bead can be added. Most saltwater cultured pearls are grown with beads whereas most beadless cultured pearls are grown in the mantle of freshwater shells, mainly in China and are known as freshwater cultured pearls.
The only way to differentiate a natural pearl from a cultured pearl is with the help of gemological x-ray equipment. The center of a pearl is examined where growth rings of the pearl can be seen. Beadless cultured pearls are harder to tell apart than those grown with a bead. In contrast to cultured pearls, imitation pearls can be determined through the help of a microscope. Just by rubbing two pearls together one can tell whether or not they are real. Both natural and cultured pearls will feel somewhat grainy whereas imitations will feel completely smooth.
Though cultured pearls are not “natural” to the full meaning of the word, they are the closest thing to it these days. The few natural pearls that exist are worth hundreds of thousands of dollars and are mostly used for collecting purposes. Rarely will one find a strand of natural pearls. For all intents and purposes, cultured pearls are the new “natural” pearl.