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Pearls have fascinated people all over the world for hundreds and hundreds of years. They have magic and mystique, a warmth and glow, and are the only gem created by a living organism.
Pearls are found in pearl oysters, although it wasn’t until the late 19th century that people fully understood how pearls were created. It was then that the relationship between pearl oysters and parasites was discovered.
It is when a foreign body of some sort, such as a grain of sand or a parasite finds its way into the oyster that it reacts. It coats the irritant with layer upon layer of the pearly substance known as ‘nacre’, and this gives the pearl its unique appearance and iridescent beauty.
This is the natural pearl, but its rarity and high price could not satisfy the demands of the consumers. What was needed was a way to guarantee a steady supply, and this lead to the discovery of the cultured pearl.
Culturing is a way to entice oysters to produce round pearls on demand. In this case, humans rather than nature introduce the irritant. The secret is to insert a piece of oyster epithelial membrane (the lip of mantle tissue) with a nucleus of shell or metal, into an oyster’s body. This causes the tissue to form a pearl sack, and that sack then secretes nacre to coat the nucleus, thus creating a pearl. |
How Pearls are Created
Pearls are found in pearl oysters. When a foreign body of some sort, such as a grain of sand or a parasite, finds its way into the oyster it reacts. To protect itself it coats the irritant with layer upon layer of the pearly substance known as 'nacre', and this gives the pearl its unique appearance and iridescent beauty.
The pearls most of us wear today are cultured pearls, their existence initiated by humans who insert a small object into an oyster or clam. The clam coats the foreigner with nacre, just like the natural process, thus creating the pearl.The depth of the nacre coating depends on the type of creature involved, the water it lives in, and how long the intruder is left in place before it is removed. As nacre thickness increases, so does the quality and durability of the pearl. |
Keshi Pearls
Keshi pearls are formed when the oyster rejects and spits out the implanted nucleus before the culturing process is complete, or the implanted mantle tissue fractures and forms separate pearl sacs without nuclei. These pearl sacs eventually produce pearls without a nucleus.
Keshi may form in either saltwater or freshwater pearls. They are generally small in size and, because there was no nucleus to guide the ultimate shaping of the pearl, their shapes vary widely. Keshi come in a wide variety of colors, and tend to have high luster and even rare orient. This is due to their solid-nacre composition.
Because the implanted nucleus of the pearl has been expelled by the oyster, the resulting keshi pearl is 100% nacre. This gives it an especially lustrous and shimmering surface quality. Most keshi, in fact, have a greater lustre than even the best-quality cultured pearls. The fact that keshi pearl are solid nacre does not, however, give them the classification of natural pearls. This is because keshi are a bi-product of the culturing process, not a natural occurrence. |