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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

DIAMOND


DIAMOND (Diamant—Diamant—Алмаз) (Pliny, A.D. 77). Corruption of Gk. adamas, the invincible, alluding to its hardness.

Composition & Properties. Crystalline carbon, symbol C, cubic system. Impurity elements: nitrogen, boron, sulfur, oxygen, and hydrogen. Hardness 10. Density 3.5. Cleavage perfect in four directions. Fragile. Diamond luster diamond. It is unsolvable in acids and alkalis. Burns down at 850°С. It is not moistened with water, but sticks to fatty admixtures. Diamonds occur in the form of regular crystals, which sometimes have rounded edges. The crystals are mainly “Indian” octahedrons and “Brazilian” dodecahedrons. Diamonds could be both transparent and non-transparent. Transparent ones have dead surface sometimes — it is so called frosty diamond, or they have fine non-transparent “coverings”. There are fine-grained aggregates among the non-transparent gray and black diamonds; they are called bort, their varieties in the size of a hail-stone are called chailstonbort (cheylstonbort), ones with the radial-rays structure – ballas, solid crypto crystalline ones – framesite and porous ones – сarbonado. The size of diamond varies from tiny grains to crystals over 10 cm. in cross-section. Small faceted brilliants, from 0.07 to 0.15 ct., are called melée. The perfect diamonds more than 100 – paragon. The common measure of faceted diamonds is carat, which wasn’t constant till 1914: from 0.187 g — in Bologna, to 0.216 g – in Livorno (App. 21). This is the reason of slight differences in the masses of the unique stones shown by different sources. Those differences were taken away in 1914, when the common measurement of carat was established as 0.2 g. The most wide-spread diamonds are small and middle-sized – 0.1-1.0 ct., moderate big – from 1 to 5 ct., big – 5-10 ct. Rather big diamonds – 50-100 ct. are more or less rare, and huge diamonds – more than 100 ct. are extremely rare. These two latest groups of diamonds can be called unique; usually such stones receive personal names (App. 1).

The presence of structural chemical admixtures and mineral inclusions is characteristic for diamonds. The most typical admixtures are dark inclusions usually classified as graphite. Diamonds with black inclusions are usually called pice. The high intensive level of such inclusions gives dark-gray to black color to diamonds, which stay sometimes transparent. Black diamonds from Yakutia deposits are called yakutite. Black diamonds, which have rich inclusions of magnetite, are brown in tone. Black diamonds, which are received in the process of irradiation, have dark-green tone. Now such diamonds are used more and more often in the jewelry. Besides graphite, there are more than 20 mineral inclusions of different types can be met in diamonds, among them: olivine, pyrope, spinel, magnetite, Ilmenite, enstatite and others. Diamonds from South Africa are characterized with the inclusions of pyrope. Diamonds from Ghana contain inclusions pyrrhotite, pyrite, Ilmenite and rutile. Diamonds from Russia contain inclusions chrome-diopside and chrome-spinel.

Nitrogen takes the first place among the structural chemical admixtures, which have an influence at the proprieties of diamonds. There are two types of diamonds according the percentage of nitrogen. The first type includes diamonds which have to 0.25% of nitrogen; the subtype I а, where nitrogen doesn’t influence at the color, and the subtype I b with blue color. Diamonds of I type are not transparent for the ultra-violet rays and give fluorescent light in the blue spectrum. Diamonds of the II type have not more than 0.001% of nitrogen, which also doesn’t influence at the color. The subtype II а is colorless and subtype II b is light blue and has an admixture of boron. Diamonds of the II type are transparent for the ultra-violet rays and don’t give fluorescent light, but all the diamonds give fluorescent light in X-rays. This principle is a base of industrial diamonds’ separators. Only transparent Dutoitspan diamonds without cracks and inclusions are regarded as gem-quality ones. Faceted diamonds or brilliants are divided in Russia into groups according the level of defectiveness (pureness and color of stones) and also according the size and the type of facets. The most valuable are colorless stones, the less valuable are yellowish-brown ones.

Color and optical effects. From colorless or pale (with light tones) to bright colored: rose-lilac, yellow, green, light-blue and dark-blue, milky-white, gray and black. Bright colored stones are called fancy diamond. Yellow stones are called canary diamond, Cape diamond or Cape stone from Rep. of South Africa; yellow stones of low quality – Kimberly diamond; yellow-brown – champagne diamond; yellow-green diamonds from Brazil – Bahia emerald; stones colored from brown to black – Savoy diamond. If there is gray color in diamonds they are called siderite or bakan, and steel-gray diamonds are called tiffanyite. Among natural black diamonds, which are offered at the market, the most part are low-quality ones, improved with the method of ionizing irradiation or with high-temperature annealing in vacuum. Irradiated diamonds are really dark green and they can keep residual radioactivity. Under heating their color is unstable. Color of black diamonds, received with annealing, is thermo-stable because of the inner graphitization of the stones under the temperature more than 1000ОС. However, black inclusions are formed in the segments lose to the surface, where there are many cracks. Synthetic technical diamonds can be classified to this group; they are enriched with inclusions of metals-catalysts. Natural black diamonds can be translucent with a great amount of inclusions and uneven color. In this case black diamonds include magnetite, and gray diamonds – native iron and hematite. Besides, to black diamonds also microcrystalline aggregates of the type of carbonado can be ascribed. As inclusions there are amorphous carbon, native iron, copper and silver, hematite, magnetite and other compounds of iron and chrome in them. Beside black diamonds they use turbid white diamonds in jewelry now. Diamonds often display fluorescence because of hydrocarbon inclusions. Colors of some diamonds can be changed by annealing or through the type of enlightenment; such stones are called chameleonic diamonds.

Strong luster of diamond depends on the high degree of light-refraction in the faceted stones – brilliants. It is characterized with the play of color, or effect of fire – there is so called iris diamond. The effect is produced by light-dispersion – decomposition of light into the spectral elements. The measure of dispersion is the difference between the points of refraction of red and violet colors. Diamond has high level – 0.063. Blemishes and high tension in the structure lead sometimes to the anomalous double refractions of isotropic diamonds. If a diamond is cut badly – and the deepness of a pavilion is too low – light is reflected from a girdle through a table facet; it is called the effect of the fish eye. Such brilliant is usually called eye diamond. There are also diamonds with the effect of opalescenceiris diamond or with the effect of asterismstar diamond.

Deposits. Diamonds are rather rare stones in the nature, because they are formed under the high pressure at the 200 km. deep, under the temperature over 1200ºС. Their absolute age is from 16 million till 1.7 billion of years. From the point of view of conditions of formation their deposits can be indigenous – basic or secondary – fields. At first they were mined mainly from the modern and fossilized fields, which give even nowadays to the 85% of the raw materials. Later, the indigenous deposits were found out: there were intrusion kimberlitic pipes, lamproite dikes, alkali-basaltoids and metamorphic eclogites. Kimberlitic pipes have the biggest practical value. However, diamonds are found only in the half of 1,000 known pipes; and only 50 pipes have diamonds in industrial quantity. The diameter of the biggest pipes are to 1,650 m. Diamonds were found also in meteorites and some rocks – impactites, which passed through the process of shock metamorphism at the moment of the falling of meteorites. There are usually fine-grained diamonds in them – sometimes in a great quantity.

The first diamonds in Russia were found on the Northern Dvina River in the 17th cent. Later, in 1829, three diamonds were found in the Middle Urals at the Krestovozdvizhenskiy mine. In 1936, on the territory from the Northern to Southern Urals 300 diamonds in 18 places were found. The biggest diamond was about 3 ct. In 1938-1939, the first diamond fields were found along the rivers Koiva and Vizhayu in the Middle Urals. In 1945, poor fields were found in the middle reaches of the Chusovaya river basin. The industrial mining in the Northern Urals was opened in 1955; diamond fields on the Vishera River gave 80% of jewelry output. In Siberia the first diamond was found in 1897 – it was happened at the goldfield in the basin of the Great Peet River, in the Yenisey Ridge. Next year one more diamond was found at the same region – on the Tochilny spring, Ol’ginskiy mine. In 1937, a diamond 0.5 mm. in size was found at the same region. But only in 1946-1947 the special searching works were begun in Siberia. In 1948, diamonds were found on the Stony Tunguska River basin – on the Little Yerema River. In 1949, they were also found at the fields in the middle reaches of the Vilyui River; in 1950 – on the tributary of Vilyui – the Markhaya River; in 1953 – on the Little Botuobiya River. In 1954, the searches of diamonds in Siberia came to the finding of the pipe Zarnitsa on the Daldyn River. In 1955, two biggest pipes Mir and Udachnaya were found; in 1960 – the pipe Aikhal; in 1969 – the pipe Internatsionalnaya; in 1975 – the biggest one Jubileinaya. Generally, more than 200 kimberlitic pipes were found in Yakutia at the territory of 1.5-million sq. km. between the Lena and Anabar Rivers. Among the biggest pipes (over 500 m. in diameter) are Zarnitsa, Mir, Udachnaya, Aikhal and Jubileinaya. There are 63 kimberlitic bodies and a diamond field Maiyat found out in the Northern part of Yakutia, on the Anabar River basin. The biggest deposit among the diamond fields – Ebelyakhskoye was found of the north of the Krasnoyarsk Krai. In the same region very interesting from genetically point of view are finds of small diamonds in some impact rocks, e.g. at the Popigai crypto explosion structure (astroblem) cross-section 100 km. At the end of 1980-s, diamond fields were found in the Amur Territory in the middle reaches of the Zeya River; in 1991 they were found lower – not far from the mouth of the Selemja River. Their inclusions are close to Yakut diamonds. In the Arkhangel’sk Region the first diamonds were found in the 18th cent., but only in 1980 the first pipe was found by drilling 120 km. north from Arkhangel’sk, 60 km. from the sea-shore. A bit later, 15 more pipes at the five kimberlitic fields were found. The Lomonosovskoye deposit was prepared for exploitation in the Zimneberezhnyi Dist. They researched thoroughly a territory of 9 km. wide with six diamond-pipes: Polyarnaya, Lomonosovskaya the 1st and the 2nd, Arkhangelskaya and Pionerskaya the average content of diamonds there is 0.6-4 ct./ton, 50% of diamonds are jewelry ones. Besides, diamonds were found on the Kola Penin. – on the Paz River, not far from the Norwegian border and Murmansk area; in Karelia – in Priladozhskii region, at Kaivomyakky and Raivimyakky, Leningrad Region Luga Dist., in the Komi Rep. – on the Middle Timan. According the information of 1995, Russia produces 25% of the world extraction of diamonds, 6.7% of faceted stones and only 0.16% of jewelry manufacturing. Now, the volume of extraction is $1.5 billion per year, and in 2005 it is used to be not less than $2 billion. In the Ukraine a kimberlitic pipe was found in the Donetsk Region. In North. Kazakhstan diamonds in size up to 1.3 mm. were found in the layer of metamorphic eclogites at the Kumdykol’ deposit. In Mongolia, in the Khangai Ridge there is a diamond pipe Shavaryn-Tsaram with a pyrope deposit.

India was the first country where diamonds were found more than 3,000 years B.C. in the Golconda fields. There are the unique in size and weight diamonds “Great Mogul”, “Koh-I-Noor”, “Pitt” or “Regent”, “Orlov” and all the famous bright colored diamonds were found (App. 1). In the early of the 17th cent. works on the diamond fields to the south of HyderÇbÇd, Andhra Pradesh State, and in the basin of the Ganges River were going. Also, in this state along the rivers Penner and Krishna, in the Ehluru Region, in the GodÇvari River Valley; and of the Orissa State – in the MahÇnad¥ and Brahmani Rivers basins, were known long ago. At the end of the 17th cent., those fields were worked out. In 1937, the first kimberlitic pipe was opened in the Madhya Pradesh State in Panna deposit. Later, at the same territory seven new kimberlitic pipes of the Madjghaon deposit were found. The 40% of diamonds were jewelry ones there. During the last years diamond pipes were fond also in the Uttar Pradesh State and in the south of the country. In Indonesia diamonds were extracted from the 5th cent. B.C. in the west of Kalimantan (Borneo) Is., in the Landak River valley; in the east – near Samarinda; in the central part of the island – near Purukchau. Mainly small diamonds are found there, but a unique one – “Rajah Mattan” or “Mattan”, 367 ct. – was also found. In the 20th cent. a kimberlitic pipe was opened in the southern part of the island, in 40 km. north from Martapura, Kalimantan Is. In China the first diamonds were found in the rivers, valleys Ilo and Shu Ho, Shandong Prov., besides in the same region the important source diamonds is Mengyin deposit. Only 25 years later in Shandong Prov. the igneous deposits were opened. There were 10 kimberlitic pipes and 12 diamond dikes, including the pipe Chanling 100 by 50 m. in size, where 20% of diamonds are gem-quality ones. The biggest diamond found there was called “Chanling”; it was 158.79 ct. In the Liaoning Prov. the pipe Binghai 240x60 m. in size was opened, generally, over 10 kimberlitic bodies were found. In the southern part of the country they were found in the Hunan Prov.; and in the eastern part of the Jiangsu Prov., where a diamond 52.7 ct. was found; also in Hubei Prov. in the eastern part diamond deposits were found.

In Brazil diamonds were found in 1723, when deposits in India and Indonesia were worked out. It made Brazil a new leader in extraction of diamonds. The content of gem-quality material in the general weight of extracted diamonds is about 50% here. At first, there were known ancient conglomerates and mica-phyllite schists with diamonds and also fields. Later, kimberlitic pipes were opened. Diamonds were found at 11 states including the biggest deposits in the states of Roraima, Mato Grosso, in the northern part of the Piauí and in Minas Gerais. In Minas Gerais diamond deposits are exploited in the Diamantina Region, in Itabira, to the northwest from Belo Horizonte in the fields near the Jequitinhonha River. In the Goiás State diamonds are in the fields near the rivers Rio Claru and Tilionies. In Mato Grosso fields on the Paraguay River were exploited, then, kimberlitic pipes were found in the Bahia State. In the states of Piauí and Parana diamond deposits were found in 1950. In Brazil the unique diamonds were found: ”President Vargas”, “Goiás”, “Darsu Vargas”, “President Dutra” (App. 1) as well as the biggest carbonado diamond “Serjio” 3,167 ct., which was found near Diamantina, Minas Gerais. In the same place carbonado diamond „Asinine head“ is found by weight of 2,000 ct.

The world next leader in the extracting of diamonds is South Africa. The beginning of its diamond history is 1867, when the first fields were opened on the Orange River, and the first diamond 21.5 ct. was found. Soon after it the first diamond pipe was found near the settlement of Kimberley, where the diamond containing rock which was called kimberlite. Later such pipes received the name kimberlite ones. In South Africa near Kimberley’s they mined pipes now: De Beers, Kimberley, and Dutoitspan, Northern Cape Prov.; Bultfontain, Free State – three pipes; Wesselton, Mpumalanga Prov. as well as a dozen more not so big pipes. Diamonds are extracted also in the seaside fields from Cape Town to the mouth of the Orange River, where the chains of deposits are at work now. In South Africa many very big diamonds – “Cullinan”, “Excelsior” – were found as well as the unique ones – “Jonker”, “Jubilee”, “Dutoitspan” and others (App. 1). Such diamond fields have been exploited in Namibia since 1908. The biggest there is Alexander Bay deposit nor far from Lüderitz. Later, kimberlitic pipes Gibeon and Berseba with high-quality diamonds were opened there. In 1955, the kimberlitic pipe Kao was found in Lesotho, in 1967, – the pipe Letseng-la-Terae, where the unique in size diamonds “Lesotho Brown” 601.75 ct. and “Anonymous” 527 ct. were found. In the same country the diamond pipe Sekameng a little bit later is open. In 1967, the first diamonds pipes were found in Botswana: Orapa, Letlhakane and Jawaneng. And the pipe Orapa, 1,670 by 1,210 m. in size, is one of the biggest in the world. Besides, there are more than 30 kimberlitic pipes and the biggest in the world diamond Jawaneng mine and the Zwapong deposit. In the early of the 20th cent, in South Rhodesia (now Zimbabwe) diamond fields were opened in the region of Gweru; 1912 – the Coloss diamond pipe, 900 by 500 m. in size, and then, the kimberlitic sill Wessels, and 29 other kimberlitic bodies were found including such rich pipe as River Rich. In Tanzania (before 1964 – Tanganyika) diamond fields were opened in 1913 near Mabuki, they have been exploited since 1925. The main regions of diamonds extracting are situated in the northern part of the country, where 400 kimberlitic pipes are known, including Mwadui pipe, 1,525 by 1,068 m, in size, near Shinyianga, and Mabuki deposit near Kwimba, to the south of Victoria Lake. In 1973 in Swaziland the Dokol diamond deposit was opened. In Central Africa the largest diamond deposits are in Congo (PRC, Kinshasa). The first diamonds of the fields were found there in 1903, and in 1946 the ingenuous deposits were opened. In Kasai Prov. diamond fields along the Kasai River and its tributaries rivers Luembe, Chicapa, Luachimo have been known since 1916, but the works were begun there only during the World War II. The first group: the Kasai, Lubudi and Bachamba deposits in Chikapa region. To the northwest from Chikapa there are two more diamond fields near Kikwiti, Bandundu. Another group of deposits is: Bakwanga (Mbuji-Mayi), to the east of the first group. Besides the fields, the kimberlitic pipes Mbuji-Mayi, Tishikwasa and Tishuba were opened there, and now 15 more pipes are known. There are black diamonds with rich inclusions of magnetite. In the Democratic Rep. of Congo (Brazzaville) diamonds were found in 1931 – in the upper reach of the Likwala River at Betu deposit. In the neighboring Gabon diamonds were extracted in the fields on the Ngunie River at Makongonio deposit. In Central African Rep. diamond fields were opened in 1914, they have been exploited since 1931 – in the regions of Bria, and Berbérati. Gem-quality diamonds take there 40% of the general output. In Angola diamonds have been extracted since 1916 – at the basin of the Kasai River, at the deposits Andrada, Lucapa, Lushila, Maludi and others, in the northwestern part of the country. There are also indigenous deposit: well known more than 600 diamond pipes and dikes including the biggest ones – Katoka, Kamafuka and Kamazambo where a great amount of gem-quality diamonds has been found. The volume of the diamonds output in Angola is $800 million per year now, and in 2005 it is used to be $1.5 billion in a year. Among the countries of West Africa, in Guinea the first diamonds were opened in 1932 – in the southeastern part of the country, and since 1935, the diamonds fields along the rivers Moa and Makona have been exploited. The unique diamond of 885 ct. was found there. In 1952, indigenous kimberlitic rock was opened there, and at the end of 1970-s diamond fields in the river-valleys Baule and Diani were found, where gem-quality diamonds took 93% of the general output. In 1980-s, the Gbinko deposit and fields Aredor, near Kissidougou (Kissidugu), were opened. In Ghana rich diamond fields were found in 1919 – along the Birim River, near Aquatia and in the low reaches of the Bonsa River, near the Gulf of Guinea. Gem-quality diamonds take 25% of the general output there, colored diamonds are often found. Kimberlitic pipes in Ghana were opened in 1943, and in Mali – in 1956. In Côte d’Ivoire (form. Ivory Coast) diamond fields were found in 1929 – on the Marauya River. In 1947, the extraction of diamonds began there at the Tortiya deposit. Gem quality diamonds took 60% of the general output. In 1962, a diamond pipe near the Boo River was found, where gem-quality diamonds took about 33% of the general output. In 130 km. to the north-east from it there is Séguéla deposit with indigenous kimberlitic dikes. In Liberia the first diamonds were found in 1911, but the extraction has been organized only since 1930. In 1957, diamond pipes were opened in the western part of the country – in the upper reaches of the rivers Lofa and Mano, and also a kimberlitic dike. In Sierra Leone diamond fields have been exploited since 1932 – along the rivers Sewa, Bafee, Bagbe and others. In the southern part of the country the kimberlitic dike “Dike Tongo”, 10 km. long, was opened; and in the eastern part, in the Angema Dist, the effective one for diamond extraction region Kondu was found. In 1945, the “Victory Diamond” 770 ct. was found there, in 1972 – one of the biggest diamonds “Star of Sierra Leone” 968.89 ct., which was evaluated in $12 million; in 2002 – a diamond 1000 ct.

In Australia, to the northwest from Sydney, New South Wales, the first diamonds in the fields were found in 1851 and in 1867 – in the Maji Region, to the west of Sydney. Later, on the Eastern plateau and plain Cudgegong a great amount of diamond fields was opened. Indigenous deposits were found in the Western Australia, on the Kimberley Plateau in 1979.Ten years later, over 30 diamond pipes were opened there. The biggest deposits with pipes are full with lamproite intrusions in the province East. Kimberley are Argyle, and in West. Kimberley – Ellendale deposit and Ellendale Fitzroy diamond pipe. The later deposit contains 60- 90% diamonds of gem-quality. At the deposit Argyle mainly small diamonds are found – usually about 0,5 ct., the biggest one was 34 ct. In the Northern Territory of Australia 37 diamond pipes have been found.

In North America the first diamonds were found in the U.S.A. in 1876 – in the Wisconsin State. In such states as California, North. Carolina and Virginia diamonds were found during the works in the gold fields. In Arkansas diamonds crystals in kimberlite at Murfreesboro, Pike Co., were found. The biggest diamond “Uncle Sam“, which was found there in 1942 had the weight 40.23 ct., the brilliant made from it was 14.42 ct. In Arizona in the meteorite crater of Canyon Diablo they found crystals of diamond up to 0.5 mm. Nowadays, diamond were opened in others states, but there are no industrial deposits. In Venezuela diamond fields were opened in 1885, the extraction has been organized since 1931 – in the basin of the Caroní River, Bolívar State. Gem-quality diamonds take there 35% of the general output. In 1942, the biggest diamond “Liberator” 154.15 ct. was found there. Nowadays, in this region, near Icabarú, kimberlitic pipes Santa Elena and Icabarú were opened. Besides, diamond fields are known in the valley of the Ventuari River – San Pedro deposit, and Guaniamo deposit in the Río Orinoco basin. To the east of Venezuela, in Guyana since 1890, diamond fields have been exploited in the upper reaches of the Mazaruni River – the deposits Makapa, Tumareng (Tumureng) and Ecerecu; in the upper reaches of the Potore River – the deposit Potore; near the source of the Esseqibo River – the deposit Cuiuvini. In Ecuador and Bolivia diamond deposits were opened in 1960. Nowadays, Canada is coming to the list of world leaders in extracting of diamonds. The first 80 diamonds were found there as long ago as 1870-1899. The first big diamond, 33 ct., was found in 1920. The first kimberlitic dike was opened in the Ontario Prov. in 1946. During last years in the northern and western provinces of Canada over 400 kimberlitic pipes containing diamonds were opened. The most part of them are in the Northwest Territories, 74 – in Saskatchewan Prov., 45 – in Ontario Prov., some of them are known in Alberta Prov. Kimberlitic pipes of the middle and less size dominate among them, many deposits are kimberlitic dikes. The richest deposits were found in the Northwest Territories: Ekate main. Davick, Snap Lake, Cennedy Lake and Jericho. In 1999 works were opened at the first deposit, in 2002 Davick is activated, in 2004 – Snap Lake. The extraction of diamonds in Canada is $400 million per year; in 2005, it is used to be $1.5 billion in a year.

In general, in 1999, 111 million ct. of diamonds were extracted, including technical diamonds. The list of the unique diamonds is shown in the App. 1.

Synonyms. Adamant | Bahia, a low-quality diamond from the Bahia State, Brazil | Hailstone boart, from English “hail-stone”, which is of an equal size | Brown diamond, nitrogen-rich | Framesite, it is called in the name of a researcher P.R. Frames | Jager, a high-quality blue-white diamond | Jargon, a low-quality yellow diamond | Diamantina stone, from Diamantina deposit, multi-colored oblong, fine crystals, Minas Gerais State, Brazil | Petroleum stone, with blemish in color | River stone, from diamond fields | Smoky stone | Tiffanyite, a low-quality steel-gray diamond, it is called after the firm of Tiffany & Company in the U.S.A.

Quality improvement. Annealing can change color of some diamonds. Brown diamonds become golden, pale rose ones – bright rose, sometimes green tone weakens. Yellow color of coated diamonds, however, can be taken away only by thermochemical methods. Besides, brown diamonds are improved by the method of HPTH-processing at the apparatus of the high pressure under P=5-6 GPa and temperature 2100-2400ºK, and also by the method βHT-processing – irradiation with the flow of fast electrons and then with annealing during 24 hours in a vacuum quartz ampoule with T=1500ºK. As a result of the PHT-processing diamonds are discolored; sometimes fancy colors are produced: blue, rose, yellow, green. Colorless diamonds, which are received after such improvement, are called Pegasus diamonds or GE POL – diamonds. This name should be written on the girdle of a faceted stone. Fancy colored diamonds improved by this method are called in trade Novo diamonds. After the βHT-processing the intensity of the brown color is weakened, some crystals become yellow-green, some – red. Because of the fashion on rare colors, brilliants are improved by neutron irradiation in an atomic reactor. Fancy colors are received as a result: green, golden-yellow, red, purple or black. In this case so-called umbrella-effect appears; it is seen through a magnifier from the side of collet as dark lines, which are parallel to the facets. In the process of irradiation with electrons light blue or blue-green tone appears, which annealing can weaken. Irradiation with gamma rays can make diamond pale blue; thermo processing – amber-red. All the stones which are colored with irradiation are called irradiated diamonds or radium diamonds. To color diamonds there is also such method as diffusive covering of brilliants with boron-containing blue film, 0.25 micron thick. Such stones can be identified by more intensive tone at the edges. To take yellow covering tone away there is used covering of pavilion facets with light blue plastic. Inclusions are taken away from diamond with laser; cavity and cracks are filled with high-refracting glass, which is put inside under the pressure at the temperature 500°C. Such stones are called in trade geuda diamond, in the name of an inventor, and also filled diamond or cleared diamond. As a result of such processing their price becomes about thrice higher. After the taking inclusions away, a fine laser channel with a disc crackle stays, which looks like a little nail. Such channels are identified with a microscope by air bubbles and a structure of flow in the glass filling cracks – flash-effect on the surface of the treated cracks. It is seen because of the interference of light at the border between diamond and glass.

Cut Gems. Diamonds were used in jewelry at first in India, where they were primarily found. Till the 18th cent. India stayed the only supplier of diamonds in the world. In the ancient Indian chronicles diamonds have been mentioned under the name fariy or vajra (thunder bolt) since the 1st cent. B.C. Diamonds were delivered by trade routs from India to the other countries. There is a bronze statuette with eyes made of not-grinded Indian diamonds of Gk. work (5th cent. B.C.) in the British Museum, London. Till the methods of processing of diamonds were not invented, this stone was less in price than ruby, sapphire, pearls and some other precious stones. The invasion of Alexander Macedonian (356-323 B.C.) to India opened the way for the trade with precious stones. After it, Indian cut diamonds appeared in Rome. Pliny the Elder (23-79) in the “Natural History” gave rather full description of diamond. During the reign of the Emperor Tiberius (14- 37) the cult of jewelries made of gold, silver and precious stones became so widespread that the Senate demanded to take a law against luxury. Since the epoch of the Renaissance, diamond has taken the special attention in Europe, too. Since 1330, in Venice the first attempts to cut diamonds with the method of simple grinding of the facets of natural crystals were made. In 1456, the court jeweler of the Duke of Burgundy Ludwig van Berkem learnt to cut diamonds. In 1530, he used such faceting shape as a “rose”, then, after the inventing of a grinding circle, the possibility appeared to make more complicated cut with growing quantity of facets. Such diamonds were called brilliants (from Fr. brilliant – glistening). Since then, the effective usage of diamonds in jewelry manufacturing has been begun.

Treasure houses of European and Eastern monarchs were filled with unique diamonds and brilliants, which changed their owners many times – as it happened with the famous diamonds “Koh-I-Noor”, “Orlov”, “Shah”, “Sancy” and others. The most part of the rulers had special personnel of diamond-cutters and jewelers at their courts. In Russia the beginning of this process took place during the reign of Ivan the Terrible (1530- 1584), who invited jewelers from Byzantium. According the words of an English envoy J. Gorsey, among the treasures of Ivan the Terrible there was a “diamond, which in glistening more expensive and precious then others”. The “Diamond throne” of Ivan the Terrible was decorated with 800 Indian diamonds. In Europe the infinite passion to luxury was characteristic for the “Roi de Soleil” – Louis XIV (1643-1715). State regalia, full dresses, weapons and horse harness were decorated with precious stones. In Russia this fashion came during the reign of Catherine the Great (1762-1796). At her epoch the cut of diamonds was organized at the Peterhof lapidary factory. The Empress liked precious things and presented them generously to her retinue, and during card games she often paid with brilliants. From 1750 till 1800 over 2000 jewelers worked in St Petersburg. Many of their masterpieces are in the D.R.F., Moscow, State Hermitage and Russian Museum in St Petersburg and other museums now. There are about 5,000 brilliants in the big Emperor’s crown of Catherine the Great; and the biggest of them is 50 ct. A bit smaller stone, of 47 ct. is in the gold apple of the “globe”, and the famous brilliant, 189.62 ct., is in the Tsar’s scepter – this stone was the gift of the Count G.G. Orlov. It is also known as “Amsterdam” because it was kept in the Amsterdam bank, and “Lazarev” because I.L. Lazarev sold it to G.G. Orlov.

The discovery of diamond deposits in Brazil in 1725 stimulated the development of centers of cut and sales of brilliants in Europe. Those centers were Lisbon, Antwerp and Frankfurt am Main, cut was made in Amsterdam, Cologne and Frankfurt am Main. Brilliants became symbols of prosperity and power. One of the biggest of them – “Cullinan I”, 530.2 ct., – decorates the scepter of British Kings, and “Cullinan II”, 317.4 ct., is in their crown. Now, the biggest brilliant is a fancy cut gem of an orange-yellow color, 545.67 ct. The smallest brilliant with 57 facets has 0.0000743 ct. Faceted colorless stones are called white diamonds and colored ones are called fancy diamond. Now, milky-white diamonds are also cut; they are called fancy white diamond. The most widespread types of faceting of diamonds is an old one – with 58 facets which is based at the natural shape of crystals and an ideal one – with optimal angles, which provides the maximal glistening and the play of color in a stone. According the quantity of facets there is round, common and complete faceting and an old faceting for flat diamonds – “rose”, where weight of a stone is equal to 1/3 of a cut brilliant with the same diameter. In the 18th cent., a square-cut called “peruzzi-cut” and a cutting with rounded edges called “regent-cut” were fashionable. Flat splits of diamonds – brilliant glass – are used in jewelries as portrait diamonds. Such flat diamond with a portrait of Catherine the Great was in possession of her favorite Count A.G. Orlov. Nowadays, complicated shapes of fancy cutting of diamonds are worked out. It is possible to make even a sphere shape. Such diamond in the shape of a “pearls” is exhibited in the Smiths. Inst. Wash.

Famous Stones & Jewels. We should note a rare case, when brilliants were used in architecture. According the legends of the 1st cent. B.C., the most ancient Buddhist pagoda Shuedagoun in Rangoon (now Yangon) in Myanmar (Burma) was decorated with gilded weathercock encrusted with gemstones. The weathercock is crowned with a gold empty ball, about 25 cm. in diameter, also encrusted with colored gemstones and diamonds. The ball and the weathercock were made from 1250 kg. of pure gold; there were 4,350 diamonds and 93 gemstones on the surface of the ball, – mainly rubies and sapphires. In Czech Rep., in the Loreta abbey treasury in Prague, there is the “Diamond monstrance” decorated with 6222 diamonds. “The Order of the Holy Spirit”, donated by the King Louis XV to one of the members of the royal family, included 400 brilliants in the silver frame. This jewelry of gilded silver was made in 1699. Its size is 895x700 mm, the weight is 12 kg. There is also “The Great pearls Monstrance” decorated with a lot of pearls, red corals and gemstones including 134 diamonds and 17 rubies. It was made from gilded silver in 1740. Its height is 930 mm. its weight is 1.74 kg.

Nowadays, unique brilliants come to the collections of financial and industrial magnates, and jewelers make more and more exquisite adornments with brilliants. Among them we can note a “cake” from gold and platinum with brilliants, general weight 636.62 ct., about $8 million in price. This “cake” was exhibited at the world of fair in Tokyo in 1990. Another example of such masterpieces of jewelry art is “brilliant” brassiere, which price was $11 million; it was exhibited at the auction in Tokyo in 1995. It was made from gold tissue with brilliants about 400 ct. in general mass. Another matchless jewelry item was a $630,000 golf set. It included a club decorated with 288 brilliants (21.12 ct.), a ball with 318 stones (25.13 ct.) and a sign with 44 brilliants (4.25 ct.). Every Christmas the jeweler from San Francisco S. Mobil performs unusual gifts: a toilet seat, a fax-apparatus, a domino-set, a mobile telephone, – all decorated with brilliants. In 1997, during the VII International Watch fair in Geneva a model of clock from “Cartier” was exhibited: it was named “Carousel of Time” and decorated with the symbol of the firm – “Brilliant Panther”. “Panthers” were encrusted with 7,000 brilliants (230 ct. in general mass). Besides, dark spots on their “skin” were made from big sapphires. The price of this watch was announced as $3.5 million.

Till the end of the 19th cent., the price of a diamond more than 1 ct. was valued according the rule of Tavernier. With the growing of size and with the equal quality the prices of two diamonds are connected with each other as the squares of their masses in carats. So, according the standard price of a one-carat diamond was 100 times lower than the price of a diamond 10 ct. Contemporary evaluation of a diamond is counted according many parameters. There is a formula of evaluation: N = m\2 (m+2) K, where N – the price of a diamond, m – its mass, K – the price of a one-carat crystal of the same quality. Price-lists for diamonds are published regularly. Such price-list has been valued in Russia since March 2001. If we take the cost of colorless brilliants of the highest quality as 1, then, green diamonds will cost 1.5 times more, red ones – 2.5, grayish-blue ones – 3.8, rose ones – 4.5, purple-rose ones – 6.6. Then, yellow diamonds will be half cheaper than colorless ones, and brown diamonds – much more cheapler. The cheapest ones are black diamonds, which cost only 5% from the price of colorless brilliants. The price of an improved geuda diamond is on 30-50% less than the price of its natural analogue. The highest price – 142 232 $/ct. – was paid in 1988 for a brilliant 52.46 ct. In 1990 an excellent in purity brilliant of a pear shape with 11 edges, 101.84 ct. was sold at the price $12.76 million. So, the cost of 1 ct. of this diamond was $125,294.5. The top price for a carat was announced in 1987 – $926,315; it was paid for a violet-red round brilliant 0.95 ct.

Legends. Unusual properties of diamond became a reason and a source of different legends and beliefs. Diamond traditionally was a symbol of power and high social status. As a talisman it guarantees a victory for a warrior, activates business talents and sharpness of mind, leads a person to the chosen goal. Diamond is used to be a talisman of fidelity in marriage, that’s why a wedding ring is made usually with a brilliant. As an amulet, diamond protects against enemies as well as against attacks of anxiety and anguish, against conflicts and nightmares. Diamond is a good amulet for people of intellectual work. Diamond was used as a treatment against many diseases. People treated it as a stimulating mean, which gives living energy to a heart. Diamond has the greatest power if it is presented or received freely, without any enforcement. Astrologers suppose diamond as a stone of the Sun and the Venus. It has the greatest bio energy because it concentrates inside it the astral energy of its Zodiac sign – Aries. It’s a lucky stone, that’s why it is good for all Zodiac signs, but it is especially lucky for Taurus. In India, where diamond was found first of all, it is a national stone, as well as in South Africa. In the U.S.A. it is announced as an official symbol of two states: of Arkansas, where the national park “Diamond Crater” is situated; and of Arizona, where crystals of diamond up to 0.5 mm. are found in a meteorite Canyon Diablo.

Synthesis. In 1970, in the U.S.A. the firm “General Electric” organized synthesis of diamonds about 1 ct. for jewelry purposes. In 1985, the industrial production of diamonds began in Japan; in 1987, the firm “De Beers” announced that some synthetic technical diamonds were to 11 ct. By the middle of 1990-s’synthetic diamonds became to 30 ct. The biggest artificial diamond was 36 ct., 17 mm. in cross-section. The most perspective is the method of thermo gradient at the priming from 3 mm. in size. The characteristic feature of synthetic diamonds is their brown-yellow and greenish-yellow color as well as admixtures of nickel and platinum. In the U.S.A. all synthetic diamonds have special inscription on the girdle. Recent years, in Novosibirsk a new technology of the synthesis of diamonds was worked out instead of hydraulic press – non-press apparatus “Cutting sphere”, where under high temperatures and pressure from all sides brown, lemon-yellow, blue and colorless crystals of diamond to 3-6 ct. could be produced. Weight of the most part of synthetic diamonds is about 0.5 ct. In Novosibirsk a diamond with the alexandrite effect is produced – it changes its color from yellow to yellow-green according the light conditions. There also red diamonds are produced – in faceted shape they are nit more than 1 ct. Synthetic diamonds, as usual, with changed color, are evaluated at the level 10% from the price of natural diamonds.

Similar Gemstones & Imitations. In old times as imitation of diamond rock crystal, sapphire, topaz, zircon were used. Besides them, from the 18th cent., a cheaper imitation appeared – there were false brilliants made from glass with high refraction – paste (strass). Sometimes they are called in the name of their inventor – chemist J.F. Strass (1701-1773). Those pseudo-diamonds, or simili really are pieces of glass with brilliant faceting and metallic foil on the low surfaces. French brilliants had red foil; Bohemian brilliants were covered with mercurial amalgam. Natural titanite, scheelite, sphalerite and demantoid can be falsely taken for brown and green diamonds. Now numerous imitations from colorless synthetic stones are known – synthetic garnets, and others: rutile, sapphire, moissanite, periclase, titanate, niobate, thantalate, phianite, and spinel. Mixed stones – doublets – are also popular: from synthetic sapphire and synthetic strontium titanate (phabulite) – amourant and laser gem, from spinel and phabulite – dialite or diarita, from synthetic spinel and synthetic strontium titanatecarnegiegem. The principal criterion for differentiation of diamonds from their imitations is annealing conductibility. It is the basic principle of the most part of diamond testers, though old testers can’t help to differentiate diamonds from its imitation made from synthetic moissanite.

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