Cultured pearl - wikipedia Cultured pearl This article has multiple issues. Please help improve it or discuss these issues on the talk page. ( Learn how and when to remove these template messages ) This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. Please help to improve this article by introducing more precise citations. ( November 2010 ) This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. ( March 2013 ) A newly opened Hyriopsis cumingi, a freshwater mussel, showing rows of cultured pearls inside. A cultured pearl is a pearl created by an oyster farmer under controlled conditions. Cultured pearls can be farmed using two very different groups of bivalve mollusk : the freshwater river mussels, and the saltwater pearl oysters. Contents 1 Development of a pearl 2 Process 3 History 4 Modern industry 5 See also 6 References Development of a pearl A pearl is formed when the mantle tissue is injured by a parasite, an attack of a fish or another event that damages the external fragile rim of the shell of a mollusk shell bivalve or gastropod. In response, the mantle tissue of the mollusk secretes nacre into the pearl sac, a cyst that forms during the healing process. Chemically speaking, this is calcium carbonate and a fibrous protein called conchiolin. As the nacre builds up in layers of minute aragonite tablets, it fills the growing pearl sac and eventually forms a pearl. Natural pearls are formed by nature, more or less by chance. On the other hand, cultured pearls are human creations formed by inserting a tissue graft from a donor oyster, upon which a pearl sac forms, and the inner side precipitates calcium carbonate, in the form of nacre or `` mother - of - pearl ''. The most popular and effective method for creating cultured pearls are made from the shells of freshwater river mussels harvested in the midwestern states of the U.S., from Canada to the Gulf of Mexico. Shells with the common names, `` Washboard '' `` Maple Leaf '' `` Ebony '' `` Pimpleback '' and `` Three Ridge '' are popular for use in pearl culture due to their compatibility with the host animal, and the nacre they are to be covered by. These high - quality and sought - after shells are first sliced into strips and then into cubes. The edges and corners are ground down until they are a roughly spherical and then milled to become perfectly round, and brought to a highly polished finish. After the nucleus is ready, the next step is obtaining the mantle tissue. The mantle tissue is harvested from one oyster and cut into small pieces. After obtaining the mantle tissue from the first oyster it is time to operate on the second animal. The oyster is placed in warm water to relax the animal. Then it is gently pried open and mounted in a stand to be operated on. A small incision is made and the nucleus is inserted along with a small piece of mantle gland. The oyster is then placed back in the water and allowed over several years to coat the nucleus with nacre. The nucleus is coated in many layers of this nacre, so that when pearls are cut in half, visible layers can be seen. Process The cultured pearls on the market today can be divided into two categories. The first category covers the beaded cultured pearls, including Akoya, South Sea, Tahiti and modern big freshwater pearls ( called Edison Pearl ). These pearls are gonad grown, and usually one pearl is grown at a time. This limits the number of pearls at a harvest period. The pearls are usually harvested after one year for akoya, 2 -- 4 years for Tahitian and South Sea, and 2 -- 7 years for freshwater. This perliculture process was first developed by the British biologist William Saville - Kent who passed the information along to Tatsuhei Mise and Tokichi Nishikawa from Japan. The second category includes the non-beaded freshwater cultured pearls, like the Biwa or Chinese pearls. As they grow in the mantle, where on each wing up to 25 grafts can be implanted, these pearls are much more frequent and saturate the market completely. An impressive improvement in quality has taken place in the last ten years when the former rice grain - shaped pebbles are compared with the near round pearls of today. In the last two years large near perfect round bead nucleated pearls up to 15mm in diameter have been produced with metallic luster. The nucleus bead in a beaded cultured pearl is generally a polished sphere made from freshwater mussel shell. Along with a small piece of mantle tissue from another mollusk ( donor shell ) to serve as a catalyst for the pearl sac, it is surgically implanted into the gonad ( reproductive organ ) of a saltwater mollusk. In freshwater perliculture, only the piece of tissue is used in most cases, and is inserted into the fleshy mantle of the host mussel. South Sea and Tahitian pearl oysters, also known as Pinctada maxima and Pinctada margaritifera, which survive the subsequent surgery to remove the finished pearl, are often implanted with a new, larger beads as part of the same procedure and then returned to the water for another 2 -- 3 years of growth. White pearl necklace History Mikimoto was able to use Nishikawa 's technology. After the patent was granted in 1916, the technology was immediately commercially applied to akoya pearl oysters in Japan in 1916. Mise 's brother was the first to produce a commercial crop of pearls in the akoya oyster. Mitsubishi 's Baron Iwasaki immediately applied the technology to the South Sea pearl oyster in 1917 in the Philippines, and later in Buton and Palau. Mitsubishi was the first to produce a cultured South Sea pearl -- although it was not until 1928 that the first small commercial crop of pearls was successfully produced. The original Japanese cultured pearls, known as akoya pearls, are produced by a species of small pearl oyster, Pinctada fucata, which is no bigger than 6 to 8 cm in size, hence akoya pearls larger than 10 mm in diameter are extremely rare and highly priced. Today, a hybrid mollusk is used in both Japan and China in the production of akoya pearls. Furthermore, other Pinctada and Pteria species are also used for producing cultured pearls today. Modern industry The development of cultured pearls took much of the chance, risk, and guesswork out of the pearl industry, allowing it to become stable and predictable, and fostering its rapid growth over the past 100 years. Today, more than 99 % of all pearls sold worldwide are cultured pearls. Colored Pearls, which occur due to local chemicals inside the shell, much in the way of rubies or sapphires, can be made by inserting natural dyes into the mussel shell, e.g., cobalt chloride to create a pinkish color. Cultured pearls can often be distinguished from natural pearls through the use of x-rays, which reveals the inner nucleus of the pearl. See also Cultured freshwater pearls Imitation pearl References Jump up ^ `` Discovery of the Pearl Cultivating Technique ''. Antique-jewelry-investor.com. Retrieved 2013 - 08 - 30. Jump up ^ `` Debunking a widely held Japanese myth '' ( PDF ). The International Pearling Journal. Retrieved 2013 - 08 - 30. Jump up ^ Southgate, Paul ; Lucas, John ( eds. ) ( 2011 ). The pearl oyster. Elsevier. pp. 31 -- 34. ISBN 9780080931777. CS1 maint : Extra text : authors list ( link ) Retrieved from `` https://en.wikipedia.org/w/index.php?title=Cultured_pearl&oldid=796819097 '' Categories : Pearls Hidden categories : CS1 maint : Extra text : authors list Articles lacking in - text citations from November 2010 All articles lacking in - text citations Articles needing additional references from March 2013 All articles needing additional references Talk Contents About Wikipedia Deutsch Français Íslenska Norsk nynorsk Polski Română ไทย Edit links This page was last edited on 23 August 2017, at 07 : 02. Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: name the shellfish which is cultured to obtain pearl
Answer: oyster