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Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

PEARL


PEARLS (Perlen—Perles—∆емчуг), from Lat. name of the pearls shell “perna”. The Russ. word jemchyug is a transformation of Chinese jeng-yu or Arabic zenchug. The name pearls has been known since 1646. In antiquity and in the Middle Ages, they called pearls margarita from Margaritana shell or also fish-eyes.

Composition & Properties. Pearls are bioorganic formation of the group of aquagenic jewelry materials, composed with CaCO2 – 92%, bioorganic substances skleroprothein and conchialine – 4-14% and H2O – 2-4%. Water is performed in the composition of organics and it is partly hygroscopic. Its most content is registered in fresh-caught pearls, which is called maiden pearls. Such a pearl should be pull out of its shell not with fingers but with lips – not to let it be deformed. Hardness of pearls – 3-4, and mechanical durability of river pearls is higher than that of sea pearls. Density: 2.8-2.4 – for sea pearls and 1.3 – for freshwater pearls. Later we describe not only natural pearls but also cultivated pearls.

Natural pearls. It exists in rounded or irregular shape composition CaCO3 in shells of sea and freshwater mollusks; it is formed without the participation of humans. All the components of pearls, as well as nacre on the surface of shells, are produced by organs of inner secretion of a mollusk. The speed of growing of sea pearls is 0.38-2.30 mm./year, and that of river pearls is 0.05-0.23 mm./year. Duration of growing of a sea pearls-oyster is not more than 8-10 years, and of a river one – up to 50 years and even more. The frequency of finding of pearls in shells differs among sea mollusks – 1:40, and among river ones – 1:1000. From one shell of a sea pearl-oyster they usually receive not more than one, rarely up to three pearls, although exclusions are known. On Sri Lanka, they receive 67 pearls, in India – 87 pearls, in the Feodosya Gulf of the Black Sea – even 133 pearls from 3.2 to 5.2 mm. However, the record is finding of a Pteria shell in Japan, in which they found 620 pearls on the square of 25 cm2.

A unit of the weight of pearls is a grain. One grain is equal to 0.05 g = 0.25 ct. In Japan they have their own measures for pearls: “momme” – 3.75 gm. and “kan” – 1,000 momme, or 3.75 kg. However, recently, the weight of pearls is measured mainly in carats. According the size, pearls are classified at the Russian market in the following way: a) graded pearls – bigger than 3 mm. and more than 1 gain; b) beads pearls –2-3 mm., c) dust pearls, or seed pearls – smaller than 2 mm. and less than 0.25 grain. It is also called pearls grain. Pearls more than 4 grains are sold apiece; they are called accounting pearls. At the world market, pearls are classified after their size the following way: very small – less than 3 mm in diameter, small – from 3 to 4.5 mm., middle – 5-6 mm., large – 7-8 mm., very large – more than 8 mm. The most valuable are ideal spherical pearls, a bit less valuable – pear-shaped, then, there are oval and flattened pearls. Among gem-quality pearls, there are also irregular in shape baroque pearls, which are also called fancy pearls, wart pearls. More general name for them is wild pearls. Such samples possess their personal names after their size – monster pearls, or after the shape – drop pearls, hay stack pearls, button pearls, mandarin pearls, and also cylindrical pearls, hammer pearls and others. There is no general commercial classification of pearls, although there are general parameters for their evaluation: lustre, color, thickness of transparent nacre layer and shape. In the places of traditional collecting and selling of pearls, there are local names of sorts and categories of the evaluation of the quality. In Europe, in the highest demand are rose pearls, white and black pearls. In South-East Asia – light bluish, and in Africa – yellowish one, which is in a beautiful contrast with dark skin Negros.

Form of finding. Formation of pearls is going usually around a foreign body, which was included into the cavity of a shell. That’s why there are such names as mud pearls, sandy pearls. The disposition of a pearl in a shell determines its size, shape and sometimes its name. The most favorable place is the mantle cavity, where in a pearl sack or a cyst – an ideal in shape cyst pearl, saccule pearl or free pearl is growing. Sometimes, egg-like pearl are formed there. Pearls, which were growing in muscular tissue, usually are of less size and deformed in their shape – muscular pearls. Even more fancy shape is typical for pearls, which were growing in a lock part of freshwater mollusks – hinge pearls. Depending on the shape, they have different names: dog’s teeth pearls, alulas pearls, deer horn pearls, petal shaped pearls. Rather special half-spherical shape is typical for tumors of nacre on the inner surface of shells, which are called blisters. They are hollow inside, that’s why they are also called blister pearls, shell-shaped pearls, crop pearls, wart pearls or chicot pearls. Sometimes, on the surface of shells, there is an attached pearls; it forms a blister pearls, semi-circular pearls, fancy or turtle-back pearls.

Inner structure of pearls is radial-concentric, with exclusion of abalone pearls, which possesses porous (alveoli) constitution and Pinna pearls with radial-rayed constitution. Concentric layers in river pearls are composed with microscopic, fine lamellas of aragonite, and in sea pearls – of aragonite and calcite. River pearls differ from sea pearls with rather higher level of manganese content.

Standard of color for pearls is white, usually with cream, rose or blue tints, which is also called white pearls, gem pearls or fancy pearls, as well as clear water pearls – as gemstones. There are milky-white pearls translucent to the deep of the nacre layer. They are characterized with strong luster and bluish play of color, which comes to iridescent one when turning of a pearls. Such pearls with obvious shifting light strip are called pearl’s eye. They estimate highly rare fire pearls with bright iridescent luster resembling flashes of the aurora borealis. There are also pearls of different colors: cream, light brown, purple-red, light blue, lead-gray – clam pearls and black pearls. The nature of their color is connected with bioorganic substance and specifics of it disposition in a pearls, as well as with elements-admixtures typical for the environment, where mollusks were living. Near the coast of Australia, there are golden colored pearls, on the Philippines – yellow ones, on the Pacific coast of Mexico – green ones with metallic tint, and in the U.S.A., in the basin of the Mississippi River – purple and copper-red ones. Non-transparent brown pearls rich with conchialine are of no commercial value.

Effects. Optical effects in pearls depend on the combination of different factors. Lustre and glistening of color in the shape of a light spot depend on the combination of refracted radiation in a regular sphere of an ideal pearls. Orient – chatoyancy and play of light depend of the level of translucency and the intensity of reflected light in the outer layer. Pearle lustre also depends on the brightness of reflected from the surface of a pearls. Concentric layers of gem-quality pearls are composed with thinnest lamellas of aragonite, parallel to the surface pearls, and reflection of the sun rays from them is accompanied with the interference with partial dispersion. When the interference is dominating over the dispersion, iridescent tints are displayed. In the opposite case, pearls look dull, they is called dead pearls or unripe pearls, opposite to mellow pearls with bright luster.

Preservation. In spite of widespread ideas on the short life of pearls, their ancient analogues are found in sediments of previous geological eras. In the desert of Gobi, in freshwater sediments of the Cretaceous period (>100 million years), they have discovered well preserved fossil pearls up to 2.5 mm. in diameter. Sea fossil pearls are found more often. The most ancient pearls were found in the Upper Silurian localities in England (> 410 million years). They keep not only the shape, but even pearly luster, they are of concentric constitution, yellow and brown in color. In younger localities, from the Triassic (250-205 million years) to the Pleistocene (1.6-0.01 million years), fossil pearls keep not only pearly luster, but their color, too. On the Atlantic coast of the U.S.A., in the Tertiary sediment (25-10 million years), they discovered more than 50 gem-quality fossil pearls. Two of them were 10 mm. in diameter, the other were small. In the deposits of the same age in Japan, by Hiroshima, they found a fossil pearl 5 mm. in diameter. The biggest fossil blister pearl, 74 mm. in diameter, is exhibited in one of American museums. However, these findings are of no practical importance because of their rarity.

Preservation of gem-quality of modern pearls depends on the stability of its proprieties. Drying of conchialine under low humidity leads to cracks. Polymorph transformation of unstable aragonite into calcite is applied with increase of the volume of crystalline lattice and leads to the complete destruction of pearls. Nevertheless, there are many facts of long preservation of pearls in museum collections and in treasures. The most ancient adornments with pearls were discovered in Ancient Mesopotamia, during the excavations of the tomb of Shub Ad (about 2,600 B.C.) in the ancient city of Ur. In the Persian gallery of the Louvre, Paris there is a necklace with 216 pearls, found in Suzy (the 4th cent. B.C.). A bronze statuette of Aphrodite from the Boston Museum, the U.S.A., with perfectly preserved pearls ear-rings, is dated to the period of 465-238 B.C. In collections of the Russian Museum, SPb., river pearls are preserved more than 400 years, but sea pearls are to be destructing after 300 years of preservation. Besides, ideas on the short life of pearls – about 100-150 years – are not unreasonable, mainly because of incorrect conditions of the preservation.

Locality. Sea pearls. The main sources of gem-quality pearls are sea mollusks, mostly Pinktada. The size of their shells is from 7 to 20 cm. in cross-section, the weight reaches 10 kg. They produce pearls only at the 5-6th year of life, to the 7th year quantity of pearls is increasing radically. The places of habitation of pearl oyster shell in the world are located mainly not far from the equatorial region, between latitude 25° North and latitude 25° South. Traditional regions of collecting pearls are supposed to be the coast of the Indian Ocean from Africa to Indonesian Iss. From the region of the Persian Gulf, high-quality pearls of soft rose and cream tones come. According the classification of the best gemstones established in gemology, it is called oriental pearl. Large pearls were called here lu-lu pearls, small ones – maragan pearls. Depending on the specific place of collecting, the following trade names were adapted for pearls: African pearls, Egyptian, Indian, Red Sea, Madagascar, Ceylon, Merguian pearls – after the Mergui Archipelago in the western part of the coast of the Myanmar; Haiti pearls – after the name of the island in the archipelago of Greater Antilles. Sometimes, names were given after the places of the pearls trade, for example in India: Indian pearls, Bombay pearls, Calcutta pearls, Urian pearls, Madras pearls, Manjara pearls, Mukta pearls and others.

In the pre-Columbian times, in Central America, pearls were collected in the Caribbean basin and in the Mexican Gulf. When Spanish conquistadors came, this trade was enhanced. American pearls, which were sent to Europe in significant quantity, were called occidental pearls. In the quality these pearls were worse than oriental pearls from the Persian Gulf because of the dominancy of color tints – yellow, light blue, gray-green, bronze and metallic. From the Pacific coast of America they have sent black pearls, which were called after the places of their collecting: California pearls, La Paz pearls and Panama pearls. Weakly colored variety was called blue pearls. When the collecting became more active, new varieties and names of American pearls appeared in the trade, such as Venezuela pearls, Haiti pearls, Colombian pearls, Mexican pearls.

In the second half of the 19th cent., they began to collect pearls at the coast of Australia, and later – on Pacific islands. In Australia, the first pearls was found in 1861. Since then the city-haven Broome has become a center of collecting and selling of pearls. That’s why Australian pearls are often called also Broome pearls or yellow pearls, because it was mainly of yellow color with golden or silvery tint. Rarely, they found black pearls there, too. In the quality Pacific pearls take place between yellow Australian pearls and milky-white oriental pearls. Its varieties are also called after the places of collecting: Sula pearls, or Celebes pearls – after the former name of the Sulawesi Is., Indonesia; Manila pearls, or Philippine pearls; Tuamotu, or Tahiti pearls – from the islands of the Community, Melanesia; South Seas pearls – from Oceania or Micronesia. In the quality white Philippine pearls is better than Australian one, but worse than Madras pearls or Ceylon pearls.

Beside Pinktada shells, at the coast of seas of South-East Asia, they find rather big colonies of the Placuna mollusk – up to 400 shells on 1 m2. Because of the transparency of fine nacre shucks, it is known as glass oyster, or Chinese glass. Properties of Placuna pearls are: their lead-gray color with mica-like luster and their comparatively small size. Almost the half of collected pearls is less than 1 mm in diameter, 45% of them are from 1 to 2 mm., and only 8% are more than 2 mm. They collect such pearls for medical purposes mainly, and nacre shells are used in jewelry for incrustation.

On the territory of modern Ukraine, sea pearls was collected on the coast of Crimea – crimean pearls. Its most ancient findings were made in the tombs of the 1st cent. A.D. and in medieval tombs near Simferopol’. It proves that in the antique times there was a trade of collecting pearls. From this region so called Kafaian pearls, or Kafimian grain came to the Ancient Russian state from Kafa (now Feodosya); it was also called Surozh pearls after Surozh (now Sudak). Black Sea pearls are mainly small, rarely middle-sized, in some cases – up to 30 mm. Opposite to it, in Russia, they evaluated high quality pearls taken from southern seas, which were called Bourmitian pearls, or Gurmygskiy pearls. Obviously, this name is incorrect Ormuz pearls after Ormuz, a situated on coast of the one nominal passage connecting the Persian Gulf and the Oman gulf. Since the 2d cent. B.C., this region has been a traditional place of collecting and selling of Persian Gulf pearls, which is well-marked from Sumer texts, where collecting fish eyes, or mollusks tears (as they called pearls) had been mentioned. Nowadays, the Red Sea lost the importance as one of the sources of industrial collecting pearls.

Beside widespread pearl-oysters shells Pinktada, of commercial interest are Abalon mollusks. Nacre covering of these shells and found in them pearls are of bright green or rose color with strong luster. They are wide-spread near the coast of Florida, the U.S.A.; in Australia – near the coast of Queensland; and also near the coast of Korea and Japan. In Japan, they are called Awaby pearls. Usually it is represented to the shell blister pearls. We should also mention giant bivalve mollusk Tridacna. Its pearls are white, without nacre, with porcelain-like surface. It is called shell pearls, or clam pearls. Because of their longer life (up to 450 years), Tridacna shells of this mollusk can reach 1.5 m. in cross-section and 300 kg. in weight. Tridacnas are spread in the Indian and Pacific Oceans and on the reef of the northern coast of Australia. Found there Tridacna pearls can be very large but they are not of gem-quality. In 1934, near Philippines, in the South-China Sea, in such a mollusk they discovered a pearl, which is suggested to be the biggest one. It was more than a coconut (237x138 mm.), 31,850 ct. (6.37 kg.). Its shape resem-bled a human head in a turban, that’s why it was named “Pearl of Allah”, “Lao Tse” and “Cobba” (the last name – after its owner). In 1980, this unique pearl was sold at the auction for $200,000, and after two years it was evaluated even in $32.6 million.

Among the other pearl-oysters shells, we should mention Pinna mollusks, which are spread in the Mediterranean Sea, in the Atlantic and Pacific oceans. The size of their shells reaches 80 cm. long. Pinna pearls formed in them are also without nacre layer. They are reddish-brown, and near the coast of New Caledonia – dark red or black. For the inner constitution of these pearls radial-rayed texture is typical, as well as the absence of concentric zones and luster on the surface. Also, among non-industrial kinds of pearl-oysters shells, we should remember Pecten mollusks. In their shells, they find greenish, lilac and other colored Pecten pearls. The shape of these pearls is irregular, the quality is not high. Similar greenish pearls with pink tint are found in shells the univalve Haliotis mollusk, or sea ear shell. Usually, it is of a fancy shape, but small in size. It is characterized with the alveoli constitution and the absence of nacre concentric layers. In Japan, it is called awaby pearls. Because of its significant size it is used in jewelry. In the unique necklace “Pearls of Nordik”, named after its owner, the main treasure is an Abalone pearl, in 43 ct. One more kind of mollusks producing shell pearls is Strombus. It is found near the coast of Florida and the Bahaman Iss.; a pearl, can be found in one of 10,000 shells, and only 10% of these pearls are of gem-quality. Giant shells are called Giant’s ear because of their similarity with an ear. Strombus pearls, or conch pearls can be of a gem-quality of rose pearls or pink pearls. On their lustrous surface the flamboyant effect is displayed, resembling the moiré effect. Such pearl are rarely more than 10 ct., but there were findings up to 45 ct. The composition of these pearl is aragonite-calcite one with a small domination of the second element. Hardness and density above than at the true pearls. Large samples of these pearls are highly evaluated, but a middle-sized pearls costs not more than $20, because it can loose its luster in the sunlight. One more variety of shell pearls is Melo pearls from sea snails of the same name. Their color is yellow-brown to brown, sometimes with the flamboyant effect, but it is unstable, and quickly looses its luster. The shape of these pearls is a spherical one, the size can be significant, but jewelry value is not high.

Freshwater pearls are collected from river and lake mollusks of the kind of Unia, which are widespread in the north of Europe, in China and America. They inhabit usually fresh, running water of slow rivers. Pearl-oyster shell is covered inside with white, slightly bluish nacre. Rings of growing on the outer surface of shells show the age of mollusks, which can reaches sometimes even 50 years. The length of this shell is up to 18 cm., the weight – up to 300 gm. They find pearls in these shells: not more than 1-2 pearls for 1,000. The most stable region of their collecting is China, where even about 2,000 B.C. they took river pearls for tax payment equally with cash. This trade is flourishing nowadays, that’s why these pearls are also called Chinese pearls. They collect there small Mytilus pearls, too, which are taken from eatable oysters of the same name. This pearl is used mainly for manufacturing of medicines, that’s why it is also called drug pearls, or pharmaceutical pearls. In antique times, British islands were famous with their river pearls. It is supposed that it was one of the reasons for Julius Caesar (100-44 B.C.) to conquer the islands. As salvage, he took there a breast plate embroidered with pearls, which he presented to the temple of Venus. Pearls were collected in France, too; especially in Lorraine, they were called French pearls. The center of the trade of river pearls in Germany was the city of Passau in Bavaria – Passau pearls. In Ireland and Scotland, they collected correspondingly Irish pearls and Scottish pearls. In Scotland, on the Tay River, they collected large pearls up to 12.7 mm. in diameter and about 8.5 ct. in mass; it was called royal pearls, or Tay pearls. Findings of pearls were known by the rivers of Czech and Romania. As a result of injurious collecting, in all these countries the natural habitat of Pearl-oyster shell was radically decreased. One of the last findings in Scotland was two perfect in shape lilac pearls – 11.6 and 5.7 ct., correspondingly 11.5 and 9.3 mm. in size. They have received their personal names: “Aberneti” and “Wilhelmina”.

In ancient Russia, where there were more than 150 pearls-bearing rivers, the pearls trade was established in old times. Mainly, there were rivers of the north-western part of Russia, but in ancient manuscripts they mentioned collecting pearls in Kiev Region Russia, too. Later, pearls were collected in the Primorskiy Region, on Sakhalin and Kamchatka. The most part of northern pearls was bought at the places of collecting by Norwegian merchants and these pearls were resold in Europe under the trade name Hyperborean or Russian pearls. Pearls-hunters of the Russian North had their own, local terms. So, pearl-oyster shell was called perlovitza, from the western name “pearls”. Pearls were called odekuy or skaten’. Pearls of regular, almost spherical shape were called grain pearls, orbicular pearls. Large pearls about a pea in size were called kargapolochka, and small ones – family. Pearls a bit non-spherical in shape were called ryzik, large oval ones, more than 6 mm in diameter – cucumber, ear-like ones – green ear, pain-like – plashka, irregular ones – misshapen pearls, angulate or horned pearls. An evidence of the significant scale of the pearls trade in the Russian North is an emblem of the city of Kem’ in Karelia, which was established in 1788: there is a garland of pearls on the light blue field. The biggest pearl found there was 48 ct.; it was found on the Keret’River in 1913. In 1980s, in the northern part of Russia, on the rivers Keret’, Varzuga and others, they spent an experimental collection for pearls. It was discovered that on the most part of northern rivers pearl-oyster shell have become extinct almost completely because of pollution produced with timber rafting.

In North America, local Indians used river mollusks in food. The fact is described when they found a pearl, 100 ct., among fried mussels. When the colonization of America was begun, the so called “pearl fever” has happened. Those times, American pearls came into the market. America was even called “the country of pearls”. The first significant finding was made in 1857 – in the U.S.A., near Paterson, New Jersey they found a rose pearls, 23.25 ct., which was named “Queen of Pearls”. It was bought of the firm of Tiffany & Company in the U.S.A. for $1500, then, by the French Empress Eugenia. The richest of pearls in the U.S.A. were rivers of the basin of Missouri, which gave names for Arkansas pearls and Wisconsin pearls. In Canada, they collected mollusks of the kind of Alasmodon, which gave Alasmadon pearls. The diversity of shapes and colors was the reason of the diversity of names of pearls: wart pearls, strawberry pearls, nigger head pearls and mollusk egg pearls. Pearls with dark rings on the surface were called avian eye pearls. Injuring collecting and pollution of rivers led to exhausting and extinction of pearls oysters colonies in the most regions of the world. Nowadays, freshwater pearl-oysters are written in the Red Book. That is the reason of increasing production of cultured pearls both sea and river origin.

Quality improvement. Adornments with pearls are often kept together with other gemstones, and their owners forget that pearls are not hard. They forget also to protect pearls from drying, distractive influence of solvents and acids. Human sweat is also a weak acid, that’s why it is necessary to wash pearls from time to time in the foam of quality soap. Extinct pearls or low quality pearls are improved with mechanic or chemical methods. In the first case, the outer level is removed with grinding, and pearls are kept for a day and night in paraffin or in bone oil, then, they are polished with dust – mixed alabaster, nacre and white vitriol. Cracks are healed with drenching in warm olive oil. Under chemical restoration they carefully remove the outer level dissolving it with weak acids. Previous times, they feed pearls to poultry for the same purpose. They do the same with dark leathery pearls.

To make pearls lighter, they use sunrays, UV-lamps, or put pearls for two weeks into 10% water solution of hydrogen peroxide under the temperature of 40°C. To restore the translucency of pearls, they are put then into solution of vinyl acetate, into fat-tail lard, marrow or butter. Spotty, low quality pearls are usually colored black in a weak solution of silver nitrate with the following irradiation under the UV-lamp or in the sun-rays. Under overheating on the surface of pearls roundish, obvious cracks appear, because of which such pearls are called decraquele pearls. Coloring of pearls is made with bioorganic or non-organic dyers, sometimes after making pearls lighter in hydrogen peroxide. Coloring is made from outside, and in the case with perforated pearls – inside, too. Rose tone is received with drenching in diluted oil or spirit solution of organic red eosin, brown – in cold solution of potassium permanganate. Such color is not always stable. They use also such method of coloring as gamma-irradiation, which gives light bluish-gray to black tone in pearls because of “burning” of organic material. Cavities in the central part of a pearls can be sometimes filled with different kinds of resins.

Treatment. Sacred Indian books and clay tables from Persian burial places show the ancient roots of pearls collecting. The most ancient pearls necklace, found during the excavations in the palace of the Akhemenides in Suzy, is dated to 4,500 B.C. It is kept till nowadays and is exhibited in the Egyptian Museum, Cairo, now. In China, taxes in river pearls 2.5 millenial ago paid. In antique world pearls were among the main treasures through all the countries; it served as a symbol of authority and richness. In the Bible, pearls is mentioned more often than other gemstones – as a precious thing and as a standard of perfection. According Moslem legends, Allah has written all the former and future events on the giant white pearl called “Eternal Chronicle”. In Ancient Rome, adornments with pearls were permitted for patricians only. Usage of pearls in the state regalia can be observed from the time of ancient Chinese and Roman Emperors till nowadays. The first crown decorated with pearls was the “Diadem Aureliana” (214-275 A.D.), in the crown of the Holy Roman Empire (10th cent.) there were more than 150 large pearls, in the crown of St Stephen (1,000 A.D.) there were more than 300 pearls. On the top of crowns of Russian Tsars, from the “Cap of Monomach” on, pearls were always, because they were supposed to be a national stone of Russia. The Great Russian Imperial crown is decorated with two rows of 76 large pearls. In 1698, the order of “St Andrew the Firs-Called” was established; in its star there were 175 pearls. In the British Imperial crown, beside precious stones, there are 277 pearls. Recently, during the coronation of the Emperor of Central Africa Bocassa his mantle was made with the train, 11.8 m. long, and it was decorated with 785,000 pearls.

The first records on collecting of Russian pearls in the Pereyaslavskaya Letopis (Chronicles) are dated to the 8th cent. There is a description of Princes’ clothes embroidered with pearls. In the list of gifts for a Hungarian King from the Great Prince Ivan III a special attention was turned to a black sable with gold claws decorated with Novgorod pearls. In Russia, pearls were traditional decoration element of tsars’ costumes, it was represented in female head-dresses, clergymen’s garments, icon frames and church utensils. Embroidering with pearls was one of traditional trades in nunneries, that is why pearls were called Christly brides stone. In the 18th cent., in female head-dresses special pearls pendants “ryasny” came into fashion. In the time of the last Russian Tsar, pearl necklaces were an indispensable wedding gift for persons of the royal family. In the family of Ural manufacturers the Demidoffs they kept a four-lined necklace from pearls of the size of a hazelnut. Among the contemporary jewelries with we should mention the platinum diadem “Russian Beauty” from the D.F.R., Moscow, with 25 large cultured pearls and 928 brilliants. It was made in 1987 after the model of the beginning of the 19th cent.

The evaluation qualities of pearls depend on (in %): color – 10, shape – 15, luster – 25, thickness of the nacre layer – 25, evenness of color – 20, coincidence of sizes – 5. So, the official price of pearls (P) is calculated according the following formula: P=Pbx∑c, where Pb – is the basic price, and ∑c – is the sum of coefficients of evaluation qualities. Pearl necklaces are usually classified according their length: 14 inches (35.56 cm.) – “choker”, 18 inches (45.72 cm.) – “princess”, 21 inches (53.34 cm.) – “matinee”, 28 inches (71.12 cm.) – “opera”, 42 inches (106.68 cm.) – “rope”. Unique in length, shape and beauty Paragon pearls have their own name and history, often high-colored with legends. The biggest gem-quality pearls in the world, of the tear shape, were 60x110 mm. in size. Its mass, according different sources, was from up 575 to 605 ct. It was known under the name “Pearl of Asia” and was set in an adornment, evaluated in more than $200,000. A bit less one was the Abalone pearl “Great Rose” found in California, the U.S.A., in 1990. Its size was 70x50x28 mm., its weight was 469.13 ct., and the price at the moment of the finding was valued as $4.7 million. Then, there is the “Pearl of Hope”, in the British Museum, London, named after the collector, who had bought it in 1886 at the auction Christie’s in London for £9,000. Its shape resembles a mushroom-like cylinder, 625 mm. high, 875 mm. in cross-section at the one end and 1,125 mm. at the other end, its weight is 454 ct. This pearl is white, with bright luster and bronze tint at one side. Besides, we should mention three more pearls more than 100 ct. each one from world treasuries: 130 ct. – of the Persian Shah Nadir, 128 ct. – have the Pope Leo X, and 126 ct. – of the Spanish King Philippe IV. In the D.F.R., Moscow, there is the “Regent” pearl of the size of a dove’s egg, 84.25 ct. Previously, the property of France, it was bought in 1887, at the auction in Paris by the Countess Sumarokoff. Another egg-shaped pearl, 75.65 ct., were sold at the auction in Geneva, on May 12, 1988 for $864,280. In the list of unique pearls there are two more famous samples. The first is the “Peregrine” pearl, white, pear-shaped, of the size of a dove’s egg – 20x30 mm., 50.26 ct. (according other data, 63 or even 134 ct.). It was found near the coast of Central America, in the Panama Gulf, about 1570; it was the property of different royal houses of Europe. In 1972 it was exhibited at the show in New York. The second is “Pellegrina”, white, ideally spherical in the shape, of the size of a walnut, 27.87 ct.; it was found in India. In the early 19th cent., it was in the collection of the brothers Z.P. and A.P. Zosimov in Moscow, that’s why it was called “Pearl of Zosima” or “Moscow Pearl”. Then, it was sold to the princess Yusupoffa. In 1935, this pearl was exhibited at the show of Russian art in London. Now, it is the property of Elisabeth Taylor. The black pearl “Black Rose”, about 50 ct., decorates the crown of the British Queen. The other pearl “Star of the West”, of the similar size, found in 1917 near the coast of Australia, was evaluated in £14,000. Among unique growing together of pearls we should mention the “Pearls Southern Crux” – a cluster of nine pearls in the shape of a cross, 37.2 mm long, 18.3 mm. broad, 24.79 ct. It was found in a shell, caught in 1886 near the coast of West Australia, and was sold to Vatican for $135,000. However, there was a suggestion, that one of these pearls was added artificially to create symmetry. Large baroque pearls are successfully used in jewelries. An example can be seen in several works of art by European masters in the collections of the State Hermitage, SPb. One of them is the “Swan” pendant – an irregular pearl, 40 mm. long, not less than 40 ct., which is mounted in gold with enamel and decorated with diamonds, rubies, and pearls. Another pendant by an Ital. jeweler of the epoch of the Renaissance is a large baroque pearl, 45 mm. long, about 50 ct., it was used for a hull of a caravel. In the Grün. Gew., Dresden, Germany, there is an impressive collection of grotesque figures made by German masters of the beginning of the 18th cent. on the base of large baroque pearls from 5 to 12 cm. in size.

Recently, they use faceting in processing of pearls, but it is good only when there is a translucent upper layer.

Legends. In legends and in the epic tales of the most part of peoples of the world, there are mentions of pearls. According an Indian legend, the first adornments from pearls the god Vishnu gifted to his daughter for her marriage; from that time on, pearl was supposed to be a talisman of beloved, a symbol of virginity and loyalty. Pearls are presented to the young wife for the third anniversary of the marriage as a symbol of family happiness; the 30th anniversary is celebrated as a pearls wedding. They believe that pearl protects against evil spirits, evil events and unhappiness, it helps in long life and prosperity. A pearl was put in a wine bowl of a guest to show him good intentions and purity of thoughts. It was a common belief that a ring with a pearl protects against thieves and deceit in affairs. Special wonder-making properties were put down to pearls of irregular shape, resembling different animals. Besides, they believed that dulling pearls alerts the owner of a disease and coming death. Pearl is a symbol of the Moon; it keeps the negative forces of this planet. It was the base of the idea, that pearls attract misfortunes ad loss of hopes. Pearls are good for fanatic persons and for those, who believe in themselves. However, for travelers and actors it is nor good. Pearls were used in healing as a medicine for improvement of digestion, against impotence, asthma, hearth diseases and some others; that’s why there was such name as pharmaceutical pearls, or medicinal pearls. Astrologers take pearls as a lucky stone for those, who were born under the sign of Cancer – under the Moon on Monday, Libra – under the Venus on Wednesday, and Pisces – under the Neptune on Friday. It gives them health and good luck. In Ancient Greece, pearl was devoted to Aphrodite, it was a lucky stone of September. In such seaside countries as Saudi Arabia, India, Korea, Philippines and also France, pearl is regarded as a national symbol. In the U.S.A. pearls is a lucky stone of Sunday, in England – of Monday. It is often connected with June and at the same time it is a winter stone.

Cultured pearls. Opposite to natural pearls, it is a bioorganic nacre body inside a living mollusk, which is initiated by a human being, putting an inoculums in the form of a hard body or soft organic implantation into a shell. The high price of natural pearls and depletion of their reserves led to the necessity of an artificial cultivation of pearls oyster shells. The basics of the technology of cultivated pearls were known in China three thousand years ago. That time, they put lead figures of Buddha into shells of freshwater mollusks, and they have received the first blister cultured pearls. Similar experiments were held by Carl Linnaeus in Sweden in 1767, and at the same time in Russia, in Sol’vychegodsk – according the initiative of salt-manufacturers the Stroganoffs. In the early of the 19th cent., in Germany, similar researches were held by Hassling. But all these attempts had no practical results. In industrial scale cultivation of sea cultured pearls was organized in Japan by K. Mikimoto (1858-1954) in 1915. The essence of his method was so: he put a nacre ball covered with mantle tissue of a donor pearls oyster into another pearl-oyster shell. In average, in one from four such shells after three years a pearls is formed. But only one of four such pearls reached the commercial quality – the thickness of grown layer not less than 0.4 mm. The optimal size of an inoculum, which is put into an oyster, is 5-7 mm., the thickness of grown on it nacre layer is from 0.01 to 1.2 mm. The size of cultivated pearls in this case is 6.5-8 mm., more rarely up to 10 mm. Such cultured pearls were previously called Japanese cultured pearls, or Mikimoto cultured pearls. In 1926, this metod was adopted by the International Congress of jewelers. Now, all the cultured pearls are called so. To ensure the mass production of this pearls they organized the cultivation of oysters of the kind of Acoja, whose shells are used for inoculums-balls for Acoja cultured pearls. Sometimes, they use as inoculums defected pearls. However, this method can guarantee half-spherical cultured pearls, on the base of which they produce doublets pearls, or assembled cultured mabe pearls. To receive it, they put some half-spheres from steatite or plastic into shells. When they were covered with nacre layer on the surface of shells, they were drilled from outside. An artificial nucleus of a received pearls was taken away, and the hollow space was colored and filled with epoxy resin, and the drilled hole was closed with nacre. Under the same scheme, in Meisner pearls they fill the hollow space with glass. In jewelries the down part of a half-sphere of such cultured pearls is hidden into the frame. In mollusks’ shells, besides growing of nacre on an inoculums, not rarely small, low-quality non-nucleated cultured pearls – keshi pearls are formed. Usually, such pearls are received in the secondary usage of large Acoja oysters without transplantation of incolums. An additional influence on the growing of keshi pearls leads to fancy forms, including flattened, oval, square, triangle, cross-shaped or oblong – dog’s teeth pearls, dragon teeth pearls and others names.

As a result of improvement in technologies of manufacturing of cultured pearls in Japan in 1950s, on Biwa Lake, they opened the production of freshwater non-nucleated cultured pearls, or Biwa cultured pearls. This pearl is formed in the body of mollusk on the piece of mantle of an oyster-donor. Nowadays, almost 25% of cultured pearls in Japan are freshwater ones. This technology was assimilated in China in 1960, they receive up to 40 pearls from one shell during a period not longer than nine months. In this case, the biggest pearls, like Biwa cultured pearls, are almost ideally spherical in the shape and reach 10 mm in size. This method gives a possibility to receive tons of non-expensive freshwater non-nucleated cultured pearls, which is called freshwater rice cultured pearls because of its oblong shape and uneven surface. Now, China produces up to 1000 tons of this pearls per year.

There are many colors of cultured pearls, meantime, it is colored artificially both after the extraction from shells and in the process of growing. In the second case water is enriched up to the necessary level with certain chemical elements to receive light blue, green, orange or lilac tones or even black pearls. After Japan, which produces up to 90 tons of sea cultured pearls, under the general production up to 145.25 tons per year, the technology of it cultivation was assimilated by other countries of the region of the Pacific and the Indian Oceans. At the world market, the most highly valued is Australian cultured pearls with its brighter luster, which depends on the thicker layer of nacre. Big size of pearls is known for Burmese cultured pearls, reaching 19 mm. in diameter, and also Philippine cultured pearls, or Palau cultured pearls – up to 17 mm. in diameter. A bit smaller Thai cultured pearls and Tahiti cultured pearls – up to 13 mm. These varieties of South Seas cultured pearls are grown in big Pinktada maxima shells. On the Tahiti Is., French Polynesia, they grow black cultured pearls.

Color of pearls varies from black (with red, purple, green, brown and light blue tint) to silver-gray (with copper and golden tint). The size is usually from 8 to 13 mm., the shape can be round, tear-like and baroque. The greater cultured pearls on Tahiti were 21.5 mm. in size. In 1988, such pearls, 15 mm. in diameter, was sold for $6,000. In 2000 they produce there about 15 tons of cultured pearls. In Indonesia they grow dobo cultured pearls up to 15 mm. in diameter and the thickness of nacre layer 1-2 mm.; mabe cultured pearls with the thickness of nacre layer up to 1 mm. and resembling it blister cultured pearls 13 mm. in diameter with nucleus from artificial resin, so called cuta cultured pearls. The greater from cultivated pearls, 40 mm in diameter and 138.25 ct., was registered in the Book of Guinness in 1992. The highest price for one pearl of exclusive quality was $25,000. The most safe, non-destroying method of diagnosis of pearls and differentiation of cultured pearls from natural pearls is the method of Roentgen calculative microtomography, invented in Russia. Coloring of cultured pearls can be produced with the same method as for natural pearls, with the exception of the fact, that sometimes they use colored inoculums for this purpose.

Synonyms. ~ cultured pearls: imperial ~, keshi ~, Jap.; lustrous ~; Palau ~, after the place of production on the Palau Is., the Carolina Archipelago, the Philippines Sea; poppy grain ~.

Imitations. One of the most well-known examples of artificial pearls, which have existed since pre-historic times, are beads cut from incrassate parts of shells – Takara pearls. Similar imitations from nacre shells of lake snails are oil pearls, oiled pearls, or Antilles pearls. They made imitations from well-milled and the pressed nacre – there are Indian’s pearls. Beside these ones, they use coralsolivet pearls, rounded tumors in cavities of elephants’ tusks – ivory pearls, dugong pearls – sea cow teeth pearls, bamboo pearls – opal contractions in bamboo or tabashir pearls; coconut pearls or palm pearls – aragonite concretions from coconuts, concretions of aragonite or calcite; cave pearls, which are formed in caves from callareous solutions; satin pearls turned from fine-fibrous aggregate of aragonite or calcite, as well as gypsumalabaster pearls. Artificial imitation Angelo pearls possesses three-layered clad on the nacre nucleus, made from plastic-like material and varnish, which gives the effect of pearls luster. However, the most popular are imitations from glass. In Ancient Egypt, they used, for the first time, glass beads covered with silver and then with one more layer of glass. Skilled Vénetian were glass-blowers of the 16th cent. able to produce hollow glass beads filled with wax – wax-filled pearls, girasol pearls. In 1680, a Frenchman Jakeaut improved this imitation – he has used for inner covering of beads pearls essence, composed on the base of scales of small fishes. These beads were called Roman pearls, or hollow pearls. In 1867, also in France, Bourguillon has opened the manufacturing of glass beads filled with wax, clad outside in pearls essence, composed from gelatin emulsion, made from fish scales. Alcoholic solution of this emulsion was used to cover glass imitations – it gave especially lustrous surface. After the name of the inventor and his city, this imitation was named Bourguignon pearls, or Paris pearls. Complete beads with the same clad were called massive pearls, or Sheba pearls. Nowadays, instead of pearls essence they use for such clad mineral substance on the base of bismoclite – bismuth chloride or hydrocerussite,as well as guanine – an organic composition, from Span. “guano”, after the discovery location in birds’ excrements in Peru. Imitation with chloride of the titan has received the name titan-pearls. Bismoclite in the Australia near Bygoo is found, New South Wales.

The composition of guanine is C5H3(NH4)2N4O. Monoclinic system. Lamellar micro-crystals of guanine display chatoyancy because of diffraction and interference of light. Evidently, this technology is used in Spain for manufacturing of Majorca pearls. They can be white, cream-rose, gray or black in color, with the size from 3 to 16 mm. Black pearls are imitated with polished balls from jetjetty pearls, from hematitehematite pearls, with concretions of goethite, extracted in Guyana – Guyana black pearls, and with meteorite glass – negro buttons or fire pearls. Cheap imitations of pearls are made from plastic clad in material resembling nacre, or from glass clad in titan – titan pearls. Micomo pearls, manufactured by the Dutch firm Homburg, is an imitation of the nacre clad in thick iridescent plastic. Imitation of pearls from acetyl cellulose refers to as cellite pearls.

Synonyms. ~ pearls: ciro ~, coral ~, Coro ~, elco ~, elite ~, ellandra ~, false ~, fish ~, Kismet ~, laguna ~, Marvella ~, or Meisner ~, – opal glass with nacre in its base; Nautilus ~, noble ~, Patona ~, Patricia ~, Patrician ~, Pompadour ~, Richly ~, Rishelje ~, tecla ~, Turkish ~, rose.

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