pearl

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Pearl,

river, 485 mi (781 km) long, rising in E Miss. and flowing S to Lake Borgne, an inlet of the Gulf of Mexico; its lower section (116 mi/187 km) forms the Miss.-La. boundary. Above Jackson, Miss., the Pearl's largest city, is Ross Barnett Reservoir, one of the state's chief water-storage areas.

Pearl,

Chin. Zhujiang, river, 110 mi (177 km) long, S Guangdong prov., S China. Formed at Guangzhou by the confluence of the Xi and Bei rivers, it flows E then S past Guangzhou and Huangpu island to form a large estuary between Hong Kong and Macau. The river links Guangzhou to Hong Kong and the South China Sea and is one of China's most important waterways and one of the centers of its world trade. It is vitally important to the special economic zones that lie along its estuary, which is crossed by the Hong Kong–Zhuhai–Macau Bridge (opened 2018), the main section of which consists of a 14.2 mi (22.9 km) bridge and 4.2 mi (6.7 km) tunnel. The estuary, which also has been known as the Boca Tigris, is kept open for ocean vessels by dredging.

pearl,

hard, rounded secretion formed inside the shell of certain mollusks, used as a gem. It is secreted by the epithelial cells of the mantle, a curtain of tissue between the shell and body mass, and is deposited in successive layers around an irritating object—usually a parasite in the case of natural pearls—that gets caught in the soft tissue of the mollusk. The pearl is built up of layers of aragonite or calcite (crystalline forms of calcium carbonate) held together by conchiolin (a horny organic substance); its composition is identical to that of the mother-of-pearlmother-of-pearl
or nacre
, the iridescent substance that forms the lining of the shells of some fresh-water and some salt-water mollusks. Like the pearl it is a secretion of the mantle, composed of alternate layers of calcium carbonate and conchiolin.
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, or nacre, that forms the interior layer of the mollusk shell.

Pearls may be rice-shaped, round, pear-shaped, button-shaped, or irregular (baroque) and are valued in that order. Pearls found attached to the inner surface of the shell are known as blister pearls. The best pearls are usually white, sometimes with a creamy or pinkish tinge, but may be tinted with yellow, green, blue, brown, or black. Black pearls, because of their rarity, are often highly valued. The unique luster, or orient, of pearls depends upon the reflection and refraction of light from the translucent layers and is finer in proportion as the layers are thinner and more numerous. The iridescence which some pearls display is caused by the overlapping of successive layers, which breaks up light falling on the surface. Pearls are not cut or polished like other gems. They are very soft and are injured by acids and heat; as organic products, they are subject to decay.

Commercially valuable pearls are obtained from pearl oysters (especially of the genus Pinctada) and from freshwater pearl mussels (especially of the genus Hyriopsis). The largest natural pearl center is the Persian Gulf, which is said to produce the finest saltwater pearls. Other important sources are the coasts of India, China, Japan, Australia, the Sulu Archipelago, various Pacific islands, Venezuela, and Central America, and the rivers of Europe and North America. In ancient times the Red Sea was an important source.

Nearly all of the world's supply of cultured saltwater pearls is produced by the Japanese, who have perfected the techniques of saltwater pearl cultivation. These pearls are commonly produced by placing a small mother-of-pearl bead enclosed in a piece of mantle tissue in the body of the oyster. The oysters are then placed in cages that are suspended into sheltered bays for the period of time (up to 4 years) required for pearl formation.

Freshwater pearl cultivation is dominated by the Chinese. To produce freshwater pearls, a small piece of mantle tissue from one mussel is placed into a second mussel; shell beads and small seed pearls are also used. The quantity of freshwater pearls produced far exceeds that of saltwater pearls, and freshwater pearls are also significantly cheaper. Although many freshwater pearls are irregular oblong "rice pearls," round and near-round pearls are also produced. Inferior Chinese pearls are crushed and used in cosmetics and medicines.

Bibliography

See N. Landman et al., Pearls (2001).

What does it mean when you dream about a pearl?

The pearl is sometimes associated with the feminine principle, lunar forces, intuition, and water (all of which are identified with the unconscious). Mother of pearl lining the shell of the abalone suggests a fetus emerging to life. Alternatively, pearls in a dream may symbolize “pearls of wisdom” regarding a new idea or venture or a warning not to “cast your pearls before swine” by compromising oneself or one’s values.

pearl

[pərl]
(materials)
A dense, more or less round, white or light-colored concretion having various degrees of luster formed within or beneath the mantle of various mollusks by deposition of thin concentric layers of nacre about a foreign particle.
(pathology)
Rounded masses of concentrically arranged squamous epithelial cells, seen in some carcinomas.
Mucous casts of the bronchi or bronchioles found in the sputum of asthmatic persons.

pearl

June. [Am. Gem Symbolism: Kunz, 319–320]

pearl

emblem of discreet shyness. [Gem Symbolism: Kunz, 69]
See: Modesty

pearl

2. a pale greyish-white colour, often with a bluish tinge

PEARL

(language, mathematics)
A language for constructive mathematics developed by Constable at Cornell University in the 1980s.

PEARL

(language, real-time)

PEARL

(language, education)
One of five pedagogical languages based on Markov algorithms, used in "Nonpareil, a Machine Level Machine Independent Language for the Study of Semantics", B. Higman, ULICS Intl Report No ICSI 170, U London (1968). Compare Brilliant, Diamond, Nonpareil, Ruby.

PEARL

(language)
A multilevel language developed by Brian Randell ca 1970 and mentioned in "Machine Oriented Higher Level Languages", W. van der Poel, N-H 1974.

PEARL

(language, tool, history)
An obsolete term for Larry Wall's PERL programming language, which never fell into common usage other than in typographical errors. The missing 'a' remains as an atrophied remnant in the expansion "Practical Extraction and Report Language".

["Programming Perl", Larry Wall and Randal L. Schwartz, O'Reilly & Associates, Inc. Sebastopol, CA. ISBN 0-93715-64-1].

Perl

(Practical Extraction Report Language) A programming language written by Larry Wall that combines syntax from several Unix utilities and languages. Introduced in 1987, Perl is designed to handle a variety of system administrator functions and provides comprehensive string handling functions. It is widely used to write Web server programs for such tasks as automatically updating user accounts and newsgroup postings, processing removal requests, synchronizing databases and generating reports. Perl has also been adapted to non-Unix platforms. See mod_perl and LWP. See also PURL.
References in periodicals archive ?
| Dr Organic Pro Collagen Plus Black Pearl, PS9.49 (was PS18.99), Holland & Barrett MORINGA | What does it do?
Capitol Noir Swarovski Black Pearl and Sterling Silver Earrings PS25.00 ?Fabulous Black Rowan Collection Bangle shown in silver with Frost enamel PS286.00 ?Sheila Fleet River Ripples Collection, shown in silver with Ocean Hue enamel from PS125.00 Sheila Fleet?
Black Pearl Award for Best Actor and Best Actress ($25,000 each) went to Iranian Hamed Behdad ("No One Knows About Persian Cats") and Mexican Alicia Laguna and Sonia Couoh ("Northless" -- a movie by Rigoberto Perezcano which also received the Jury Special Mention Award).
Black pearls are said to be all the rage, partly because of Sharon Stone's well-reported purchase of an extravagant necklace in Tahiti--but, no matter.
Even more disturbing was the trend in the price per gram of black pearls. During the 1970s, the price per gram of black pearls rose an average of thirty three percent per year.
Copage is the author of the best-selling Black Pearls daily meditation series, and most recently of the best-seller Soul Food: Inspirational Stories for African Americans and Soul-Mates: An Illustrated Guide to Black Lave Sex and Romance.
Despite this setback, annual production is around 200 kilograms and black pearls account for 90 per cent of the Cook Islands' exports, bringing in NZ$15 million a year and employing 700 people.
This is a glossy publication that outlines the history of Black Pearl Limited--what it does, where it plans to go.
For Geographical, he visited a remote archipelago in French Polynesia to document black pearl farming.
In fact, growth in the mainland market for black pearls has shown up in the profit margins of more than a few Hawaii-based black pearl jewelry companies.
Black Pearls: Paintings by African-American Women (Pomegranate, $14.99, ISBN 0-764-92346-3), is an engagement calendar with art by Synthia Saint James, San Kelly Cecilio, Melinda Moore Lampkin and Earthlyn Marselean Manuel.
Three black pigments for film masterbatches, Black Pearls 3030, 4040 and 4060, are said to each provide a particular performance balance in terms of opacity, weatherability, film smoothness and dispersability.