Cultured pearl: Difference between revisions

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A{{short '''cultured pearl''' is a [[pearl]]description|Pearl created by a pearl farmer under human-controlled conditions.}}

{{refimprove|date=March 2013}}

==Development of a Pearl==

[[File:Akoya pearl.jpg|thumb|Cultured ''akoya'' pearls]]

A pearl is formed when some sort of small object, typically a parasite or piece of organic matter, becomes embedded in the tissue of an [[oyster]] or [[mollusk]]. In response, the mantle tissue of the mollusk secretes [[nacre]], a combination of crystalline and organic substances. As the nacre builds up in layers, it surrounds the irritant and eventually forms a pearl.

'''Cultured pearls''' are pearls which are formed within a cultured [[pearl]] sac with human intervention in the interior of productive living [[Mollusca|molluscs]] in a variety of conditions depending upon the mollusc and the goals.<ref>{{cite book |title=The Pearl Book |publisher=[[CIBJO]] |year=2020 |page=11}}</ref> Having the [[nacre|same material]] as natural pearls, cultured pearls can be cultivated in [[seawater]] or [[cultured freshwater pearl|freshwater]] bodies. Over 95% of the pearls available on the market are cultured pearls.

Natural pearls are those pearls which are formed in nature, more or less by chance. Cultured pearls, by contrast, are those in which humans take a helping hand. By actually inserting a foreign object into the tissue of an oyster or mollusk, pearl farmers can induce the creation of a pearl. The same natural process of pearl creation takes place.

== Development of a Pearlpearl ==

==The Pearl Industry==

[[File:Pearl Section.svg|thumb|upright|Cross-section of a cultured and a natural pearl]]

Modern-day cultured pearls are primarily the result of discoveries made in the late 19th and early 20th centuries by the [[Japan]]ese researchers Mise and Nishikawa. Although some cultures had long been able to artificially stimulate mollusks into producing a type of pearl, the pearls produced in this way were only blister and mabe, rather than actual round pearls. What Mise and Nishikawa discovered was a specific technique for inducing the creation of a round pearl within the gonad of an oyster. This technique was patented by [[Kokichi Mikimoto]] shortly thereafter, and the first harvest of rounds was produced in 1916.

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 (mollusc)|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.

[[Pearl#Natural pearls|Natural pearls]] are initiated in nature more or less by chance, but cultured pearls are human-initiated, formed by inserting a tissue graft from a donor mollusk, upon which a pearl sac forms, and the inner side precipitates calcium carbonate, in the form of nacre or "mother-of-pearl".

This discovery revolutionized the pearl industry, because it allowed pearl farmers to reliably cultivate large numbers of high-quality pearls. In contrast to natural pearls -- which have widely varying shapes, sizes, and qualities, and which are difficult to find -- cultured pearls could be "designed" from the start to be round and primarily flawless. The oysters could be monitored for up to two years until each pearl is fully formed, thus better insuring their health and survival. And the pearls could be grown by the tens of thousands, thereby bringing their cost down to a point where pearls became accessible to large numbers of people around the world.

The most popular and effective method for creating cultured pearls utilizes the shells of freshwater river mussels harvested in the Midwestern 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.

In short, 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. Led by pearl pioneer [[John Latendresse]], the United States began culturing freshwater pearls in the mid 1960's.

<!-- poorly written how-to, not encyclopedic

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. -->

== Pearl nuclei: the core of modern cultured pearls ==

In [[Palm Island, Queensland]], [[Australia]] in 2004, in a now closed pearl farm, pearl oysters commenced life as spats from hatchery farms, and were then grown for two years on a pearl farm. They were then seeded as pearls and cultivated for another two years, suspended on long lines, some on the surface, others below the surface. Each line had vertical lines dropping from it at one metre intervals with about six to eight shells on each vertical line. When the pearl had grown, two to three years after seeding, it was removed and the shell was reseeded to produce a second, bigger, pearl. Shells had a commercial production life of 10 to 12 years, producing roughly every two years.<ref>{{cite web|url=http://www.austlii.edu.au/cgi-bin/disp.pl/au/cases/cth/aat/2004/268.html|title=The Manbarra People and Great Barrier Reef Marine Park Authority and Anor [2004] AATA 268|author=Administrative Appeals Tribunal|publisher=Australasian Legal Information Institute (AustLII)|date=[[15 March]] [[2004]]|accessdate=2007-02-03}}</ref>

[[File:White pearl necklace.jpg|thumb|upright|White pearl necklace]]

A pearl nucleus or a bead for cultured pearl is a sphere (usually) or other shape (occasionally) formed only by cutting and polishing a nacreous shell used to accommodate the nacre secreted from a graft of mantle tissue, that eventually forms the centre of a beaded cultured pearl.<ref>{{Cite book |last=CIBJO |title=THE PEARL BOOK |publisher=CIBJO standard |year=2010 |pages=8}}</ref> While the material can be of anything that does not negatively affect the health of a pearl oyster, the modern age pearl cultivators normally use [[Freshwater bivalve|freshwater bivalves]] that either come from the US [[Mississippi River]] or China's freshwater bodies located in [[Hunan]] and [[Jiangxi]] provinces.

===Nucleation===

Prior to the [[1930s]], exporting pearls was the main economic activity of [[Kuwait]]. When the Japanese invented cultured pearls, the Kuwaitis decided to drill for [[Petroleum|oil]]. This was the start of the Kuwaiti oil industry.

[[File:Perles de Tahiti (1).JPG|thumb|left|Cultured dark Tahiti {{nowrap|pearls{{hsp}}{{mdash}}{{hsp}}}}one of the pearls is cut to expose the manmade nucleus bead]]

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, [[Tahitian pearl|Tahitian]], and the large, modern freshwater pearl, the 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 Edison. This perliculture process was first developed by British biologist [[William Saville-Kent]], who passed the information along to Tatsuhei Mise and Tokichi Nishikawa from [[Japan]].<ref>{{cite web|title=Discovery of the Pearl Cultivating Technique|url=http://www.antique-jewelry-investor.com/discovery-of-the-pearl-cultivating-technique.html|access-date=2013-08-30|publisher=Antique-jewelry-investor.com}}</ref>

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 10 years,{{when?|date=May 2021}} when the formerly rice grain-shaped pebbles are compared with the near round pearls of today. In the last two years,{{when?|date=May 2021}} large, near perfectly round, bead-nucleated pearls up to 15 mm in diameter with metallic luster have been produced.

Cultured pearls can often be distinguished from natural pearls through the use of [[x-rays]], which reveals the inner nucleus of the pearl.

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 bivalve. South Sea and Tahitian pearl oysters, as ''[[Pinctada maxima]]'' and ''[[Pinctada margaritifera]]'', respectively, which survive the subsequent surgery to remove the finished pearl, are often implanted with a new, larger bead as part of the same procedure, and then returned to the water for another 2–3 years of growth. An experimental process using a [[radio-frequency identification]] nucleus allows the provenance of cultured pearls to be tracked.<ref>{{cite news|last1=Lazarus|first1=Sarah|date=15 February 2018|title=Pearl farming in Hong Kong: enthusiasts restock oyster beds in city waters to revive a 1,000-year-old industry|work=[[South China Morning Post]]|url=https://www.scmp.com/magazines/post-magazine/long-reads/article/2132680/pearl-farming-hong-kong-enthusiasts-restock|access-date=25 December 2018}}</ref>

Today more than 99% of all pearls sold worldwide are cultured pearls.

== Notes History==

=== Song Dynasty (960 - 1279 AD) ===

<references/>

[[File:Cultured Mabe pearl in shape of Buddha.jpg|thumb|Cultured Mabe pearl in the shape of a Buddha]]

One of the first recorded histories of cultured pearls was found in the ancient China during the Song Dynasty. The cultivation method was the same as the Mabe-pearl (half pearl) that we know of today. Instead of using the shells or saibo as the core, they used a mold to create a buddhist figure made from lead. The mold was then inserted into the freshwater mussel shell, ''[[Hyriopsis|Hyriopsis cumingii]]''.

=== Reaching Europe ===

In 1637, Mr. [[Song Yingxing]] compiled a Chinese encyclopedia called [[Tiangong Kaiwu]] ([[:zh:天工开物|天工開物]]). Chapter 18 of this collection mentioned about the pearls and the formation theory. Along the line of history and with the help of the [[Silk Road]], Tiangong Kaiwu arrived in Europe and was translated. Scientists who were fascinated by the mysteries of pearls began their quest to find out how pearls are formed.

=== Formation Theories and Cultivation Research ===

From the 16th to the 18th century, the western world advanced in pearl research as new technologies, such as microscopes, developed. Scientists began more sophisticated research on pearl formation, developing new theories one after another. ''Disease Causation Theory (Guillaume Rondeletius, 1507 - 1566), Egg Causation Theory (Chauveton, 1578), Sand Grain Causation Theory (Sir R. Redding, 1674), Parasite Causation Theory (D. E. von Baer, 1830),'' and the ''Pearl Sac Theory'' ''(William Saville Kent, 1893)'' were all theories that tried to explain the pearls' formation. <ref>{{Cite journal|title=A History of the Cultured Pearl Industry|journal=[[Zoological Science]]|year=2013|doi=10.2108/zsj.30.783|doi-access=free |pmid=24125642|last=Nagai|first=Kiyohito|volume=30|issue=10 |pages=783–793|s2cid=1429376}}</ref>

=== The Rise of the Modern Cultured Pearl Industry ===

[[Mikimoto Kōkichi]] 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&nbsp;– although the first small commercial crop of pearls was not successfully produced until 1928.<ref>{{cite journal|last=George|first=C. Denis|url=http://www.pearl-guide.com/J-F-M%202008.pdf |url-status=dead |archive-url=https://web.archive.org/web/20130819234633/http://www.pearl-guide.com/J-F-M%202008.pdf|archive-date=2013-08-19|title=Debunking a widely held Japanese myth |journal=The International Pearling Journal|via=Pearl-Guide.com|access-date=2013-08-30}}</ref>

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&nbsp;cm in size, hence ''akoya'' pearls larger than 10&nbsp;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 (bivalve)|Pteria]]'' species are also used for producing cultured pearls today.<ref>{{cite book |title=The pearl oyster |editor-last1=Southgate |editor-first1=Paul C. |editor-last2=Lucas |editor-first2=John S. |year=2011 |publisher=Elsevier |isbn=9780080931777 |pages=31–34 |url=https://books.google.com/books?id=SzkhMsW7Q14C&q=Pteria+sterna&pg=PA63 }}</ref>

===Modern industry===

[[File:Bi quyet phan biet ngoc trai tu nhien va nuoi cay 1.png|thumb|left|X-ray of a cultured pearl set in jewelry]]

In short, theThe 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, Ledmore bythan pearl99% pioneerof [[Johnall Latendresse]],pearls thesold Unitedworldwide Statesare begancultured culturingpearls. freshwaterColored pearls, which occur due to local chemicals inside the shell, much in the midway of rubies or sapphires, can be made by inserting colored minerals into the mussel shell, e.g., [[cobalt chloride]] to create a pinkish 1960'scolor.

Cultured pearls can often be distinguished from natural pearls through the use of [[xX-raysray]]s, which reveals the inner nucleus of the pearl.

==See also==

*[[Cultured freshwater pearls]]

*[[Imitation pearl]]

==References==

{{Reflist}}

==External links==

* {{commonscat-inline}}

*[http://www.pearl-guide.com/cultured-pearls.shtml Cultured Pearl Information Guide]

*[http://www.pearlsofjoy.com/index.asp?PageAction=Custom&ID=10 Pearl Types]

*[http://www.selectraders.co.uk/types-of-pearls-2.html Cultured Pearls]

[[Category:Pearls]]

[[Category:Japanese inventions]]

[[Category:20th-century inventions]]

[[de:ZuchtperlePerle#Zuchtperlen]]