A natural pearl is a pearl that forms in nature with no human intervention. Natural pearls are formed when an accidental intruder enters a mollusk's shell and continuous layers of nacre grow like onion skins around the particle. Natural pearls vary in shape depending on the shape of the piece being coated.
Natural pearls have always been considered rare and are quite expensive. They are usually sold by carat weight. Most natural pearls on today's market are vintage pearls.Natural pearls of any commercial value or desirability, are extremely rare. Instead, since the early part of the 20th century, cultured pearls have supplanted natural pearls as the most common and available pearls. Single natural pearls are often sold as a collector's item, or set as centerpieces in unique Pearl jewellery. Very few matched strands of natural pearls exist, and those that do often sell for hundreds of thousands of dollars.
The Great Depression effectively slashed the value of the natural pearl, but there is no doubt that it had been some time coming. The introduction and advance of the cultured pearl hit the pearl industry hard; it had pearl dealers publicly disputing over the authenticity of these new cultured pearls, and left many consumers uneasy and confused about the much lower prices. Essentially, it damaged the image of both natural and cultured pearls alike. By the 1950s, an era of every woman being able to own her own pearl necklace had begun, and natural pearls were reduced to a small, exclusive niche in the pearl industry.
Natural pearls are less transparent than cultured pearls. If you place a natural pearl against a dark background—like a box lined in black cloth—and put it under a strong light, the natural pearl will look like a small, white, homogenous ball with no discernible inner rings. When you do the same to a cultured pearl, you will see a thin brown line between the nacre layer and the nucleus of the pearl.Because of their rarity, natural pearls are hardly ever found in most pearl jewelry stores. Most pearls for sale in the market today have been cultured.