Pearl Farming
Cultured pearls are grown on pearl farms, where several thousands of oysters can be nucleated and then cared for over the 2-5 years required for a pearl to develop. Like any other form of farming, the culture of pearls is as dependent on luck as it is on skill. An entire bed of oysters can be completely devastated by such unpredictable and uncontrollable factors as water pollution, severe storms, excessive heat or cold, disease, and many other forces of both man and nature. Although pearl farmers attempt to control as many of these variables as possible, pearl farming can indeed be a risky business!
Before the farmer can even begin nucleating oysters to begin the process of pearl production, there must be oysters to nucleate. In the early days of the cultured pearl industry, oysters were simply collected from the sea. Although some farmers continue using this method today, the more-modern practice is to essentially breed the oysters. The pearl farmer collects oyster sperm and eggs from high-quality oysters already on the farm, and then uses the sperm to fertilize the eggs and create a new generation of oyster larvae.
The larvae are allowed to float freely in the water under controlled conditions until they are a few weeks old, at which point they attach themselves to "collectors" which have been provided by the farmers for this purpose. (In the wild, the larvae would attach themselves to a rock or similar object at this point in their development.) Over a period of a few months, the larvae develop into baby oysters. They are then generally moved into a separate "nursery" area of the farm, where they are tended for perhaps 1-2 years, until they have grown sufficiently to be nucleated.
The process of nucleation is a surgical procedure whereby a foreign object is implanted into the oyster. This object causes irritation, which the oyster counteracts by secreting nacre to surround the object, thereby producing a pearl. Two basic methods of nucleation are used.
Saltwater oysters are generally nucleated using a "bead" prepared from mother-of-pearl. The bead is first surrounded by a small piece of mantle tissue taken from a donor oyster, and then the bead and tissue together are implanted into the oyster. The bead serves as a mold, or nucleus, around which the pearl develops. The resulting pearl will contain the bead at its center (where the bead can be detected by x-rays), and the pearl will tend to develop in the same general shape as the original bead.
Freshwater mollusks are generally nucleated using a piece of mantle tissue only, without a bead. The pearl develops around the mantle tissue, which can over time deteriorate, leaving a pearl that is composed almost entirely of nacre.
After nucleating, the oysters are provided a few weeks to recover from the surgery. During this time, some of the oysters may reject and expel the implanted nuclei; others may become sick or even die. Most, however, will recover fully. The oysters are placed in cages or nets and moved into the oyster bed, where they will be tended as the pearls develop. Depending on the type of oyster, this process can require anywhere from a few additional months to several more years!
All the while that the pearls are developing inside the oysters, the pearl farmers pay close attention to water conditions, weather, and other factors which can influence both the health of the oyster and the development of the pearl. Various oysters, for example, require various levels of water temperature to thrive and produce the best pearls. The farmers will often raise or lower the oyster cages in the water to help control the temperature -- lowering the cages to cooler depths when the weather is warm, or raising them nearer the surface warmth when the weather is cool. The cages are often lowered in storms as well, to keep the oysters as safe as possible from surface turbulence. Water pollution is also a continuing concern, and pearl farmers take numerous steps to insure the cleanliness of the water in which their oysters live.
After the pearls have been allowed to develop fully, they must be harvested. The pearls are extracted from the oysters, then washed, dried, and sorted into general categories. Sometimes the pearls are polished by tumbling them in salt and water. The pearls are then sold to jewelers, manufacturers, and pearl dealers.
From Pearl-guide.
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