Most pearls that you see in the world are cultured pearls, created by farming, like this Akoya cultured pearl necklace. Natural pearls, created without human intervention, are extremely rare to find.
Today, pearls are cultured in pearl farms, and it takes usually a few years before a pearl is created. Pearls can form naturally inside oysters, or they can be cultured or farmed. Natural pearls form inside oysters, mussels or clams when a small object usually a parasite finds its way inside it. Over time, layers of nacre build up and create a pearl. This process can take a long time, as nacre grows slowly over time. Cultured pearls are formed the same way, except the farmer carefully implants a piece of mantle tissue, bead or shell inside an oyster.
Most saltwater cultured pearls are grown with beads. Growth rate of nacre varies depending on the type of pearl. For Akoya pearls, it grows around 0. It is sometimes thought that the pearl is formed by the grain of sand , but this is a common myth.
Pearls are not formed around grains of sand, but either by the parasite, or by a farmer placing a piece of mantle tissue or a bead inside it. Both freshwater and saltwater pearls are usually round shape , but they can be various shapes, and some of the most unusual ones are highly prized for jewelry. Surprisingly, they come in different colors — not just white — but also gray, blue, red, green, pink and even black. Growing your own pearls is a complex procedure , and takes a long time for a pearl to form, but the end result is worth it.
They are beautiful to look at, and quite expensive. Pearls are harvested by carefully implanting a small piece of mantle tissue, into the oyster.
Of course it depends Pearl farmers start the process of producing a cultured pearl in an oyster or mussel by delicately implanting a small piece of mantle tissue, the part of a mollusc that secretes shell-like material. Farmers might also add a bead of shell, typically from a freshwater mussel to help provide a nucleus for the pearl.
If this complex procedure is successful, the mollusc will start to deposit iridescent layers of nacre, slowly creating a cultured pearl. One of the first factors that influences the growth of a cultured pearl is how quickly the mollusc recovers from the implantation procedure itself. This is a particularly sensitive time. Before the growth stage of a pearl, the operated mollusc will need care and attention from the pearl farmer.
Image: Cultured pearls. In the case of Japanese Akoya oysters, this care period lasts up to six weeks, as much as three months for a large Tahitian and South Sea oyster, but for Freshwater pearl mussels this care period can be as short as about two weeks. If you are interested in the differences between the different types of pearls, learn more in our Buying Guide here.
Once the mollusc has recovered, it is returned to the pearl farm population, where the main period of growth of the cultured pearl will take place. Depending on the type of mollusc, the water cleanliness, temperature and the time of the year will all influence the rate at which the mollusc deposits its nacre to grow a cultured pearl. During this time, the molluscs will be regularly inspected by a pearl farmer, checked for sickness and cleaned of parasites. The farmer will also closely monitor environmental factors such as water temperature, food quality and any risks of pollution.
The growth rate of nacre can vary widely with around 0. This nacre layering is the beauty of the pearl. Saltwater oysters will only produce 1 to 2 pearls per typical nucleation. Akoya oysters can be nucleated with up to 5 beads but the use of only 2 is most common. The Akoya oyster dies at harvest. South Seaoysters Pinctada margaritifera and Pinctada maxima accept only one nucleus at a time but, as they do not die at harvest, they may be nucleated several times.
If a particular oyster has been successfully nucleated several times and consistently produces fine pearls, the oyster is often returned to the wild to strengthen the genes of future generations of spat. An oyster's pearl sac will secrete nacre on nearly any solid object.
This has led to countless attempts to nucleate oysters with material other than oyster shell. Success has been limited, however, and oyster shell is still the main staple of the pearl farmer as it has been since the early s. The reasons nuclei of non-standard composition has been so quickly rejected in the past is because the density of the nucleus must exactly match, or be extremely close to the density of the host mussel.
In order for the pearl to expand and contract in different environments, the nucleus must expand and contract in a compatible fashion. This is known as the thermal coefficient of expansion. The nuclei must also resist cracking, hold a high shine and remain stable over long periods of time. The material that best fits these criteria is the shell of the Mississippi freshwater mussel from the Unionidae family. This mussel has the added attribute of a thick shell, especially in the joint where the bivalve connects.
This thick shell enables harvesters to create large nuclei to be used in culturing larger pearls. The nucleus of a pearl, although it is not typically visible in a harvested pearl, is extremely important in the culturing process.
The nucleus is the seed that impregnates the oyster and produces the gem, although the process is not complete unless a small piece of mantle tissue is inserted with the bead. The bead material used to create the nucleus is almost exclusively derived from freshwater mussel shells found in the rivers of North America.
The shell harvested from these rivers is typically first transported to Asia to be worked. This process involves cutting the thick portion of the shells near the hinges into strips then into cubes.
These cubes are then shaped into perfect spheres by grinding, tumbling and polishing. These finished nuclei are then separated by size and quality. The finished product falls into different quality ranges in a similar fashion as the actual pearl.
Toggle menu. Cultured Pearls Cultured pearls are real, genuine pearls that are formed inside a living oyster with human intervention. Natural Pearls Natural pearls, on the other hand, are formed naturally by free-range "wild" oysters living at sea without any encouragement from humans. What is a Pearl Producing Mollusk? Pearl Nucleus One commonality all cultured pearls share is the nucleus.
Pearl Nucleus Composition The nucleus of a pearl, although it is not typically visible in a harvested pearl, is extremely important in the culturing process. First name. Last name. Email Address. Sign up.
0コメント