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Diamond Industry Advisory Com­mittee of South Africa PDF Print E-mail
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Tuesday, 18 September 2007

diamond Industry Advisory Com­mittee of South africa. An organiza­tion composed of delegates of the Master Diamond Cutters' Association of South Africa and the South African Diamond Workers' Union, the pur­pose of which is to assure a link with governmental authorities in all mat­ters pertaining to the diamond indus­try.

Diamondite. Trade name for synthet­ic sapphire,

Diamond-ite. A trademarked name for colorless synthetic corundum. diamondize. To set or adorn with Diamonds; also, to change into diamond.

"Diamond" Jim (James Buchanan) Brady. A famous Broadwayite and first-nighter of the Gay Nineties whose trademark was the diamond. He is said to have worn $250,000 worth at one time and to have had a different set of jewelry for every day of the month, containing a total of 20,000 diamonds.


diamond jubilee. The celebration of either a 60th or 75th diamond an­niversary; the celebration, in 1897, of the completion of the 60th year of the reign of Queen Victoria. See

JUBILEE DIAMOND.

diamond lamp. Any type of illu­minator designed specifically for diamond sales and display purposes. See diamondlux.

diamond lap. See lap

 
Diamond Gauge PDF Print E-mail
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Tuesday, 18 September 2007

diamond Gauge. A mechanical de­vice, usually calibrated in millime­ters and fractions thereof, used to de­termine the precise measurements of a cut diamond or other Gemstones.

See LEVERIDCE GAUGE, MOE GAUGE, (MILLIME­TER) SCREW MICROMETER.

Diamond Grader. An instrument de­signed and manufactured by the Gemological Institute of America. It consists of a 10x-30x binocular mi­croscope mounted on an illuminator base and is equipped with a GIA mechanical stoneholder, iris-dia­phragm light control, light- and dark-field illumination, tiltback and a turntable. Accessories for overhead lighting, proportion, and color grad­ing extend its use.

diamond grit. See diamond powder.

diamond hone. A hand-operated tool consisting of a small holder, the front part of which may contain 300- to


400-mesh diamond powder impreg­nated in resin, metal or vitrified bonds. The purpose of this tool is to recondition the slightly blunted cut­ting edges of hard, metal-tipped tools. They have many uses and come in various grit sizes. Diamond Imperfection Detector (trademark, Gemological Institute of America). An instrument similar to the Cemolite and Diamondscope, except that it employs a monocular microscope.

diamond, Indian classification.

Diamonds were classified according to Hindu castes, the finest being the Brahmin diamond (horn the highest, or priestly, caste); it was supposed to give power, friends, riches and good luck. The next in importance, the Kshatriya diamond (the military caste), prevented the approach of old age. The Vaisya diamond (merchant caste) brought success, and the Sudra diamond (worker's caste) brought all

 
Diamond Dredging & Mining Co PDF Print E-mail
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Tuesday, 18 September 2007

diamond Dredging & Mining Co. A

small prospecting and diamond-mining company in the Luderitz area, South-West africa.

diamond dressing tool. A holder containing either a diamond crystal or a lapped diamond that is used to


dress or form grinding wheels. Also called a dresser.

diamond drill. A drill (usually annu­lar) faced with bort, used for rock boring.

diamond dust. See diamond powder. diamond, early beliefs of origin of. (1) They were thunderbolts that grew when left under the soil. (2) They had sex, mated, and reproduced Diamonds, which grew when wa­tered with "May dew." (3) They came from the legendary, inaccessi­ble "Valley of Diamonds" in India, where they were guarded by venom­ous snakes. They were obtained by dropping pieces of flesh into the val­ley, to which the points of the diamonds would cling. Vultures or eagles flew the diamond-encrusted flesh out of the valley and men picked up the gems. diamonded. Adorned with dia­monds; diamondized.

diamond file. A file made of a cop­per strip into which diamond powder has been hammered. Diamond files (hones) are made in a variety of ways.

diamond, formation of. Under ex­treme pressure and temperature existing at a hundred miles or more below the earth's surface, carbon crystallizes as diamond, rather than as graphite which is the lower pres­sure and temperature polymorph of diamond. Diamonds are transported from depth to the surface in volcanic conduits called kimberlite pipes. Kimberlite, the host rock material for the diamond, is a type of peridotite. When kimberlite is exposed at the surface, it decomposes and disinte­grates releasing the diamonds which


A bar is slightly less than 1 atmosphere or 14.5 pounds per square inch (=psi). A kilobar is 1000 bars or 14,500 psi.

Diamond-graphite equilibrium diagram show­ing temperatures and pressure at which dia­mond forms.

may be deposited and concentrated in alluvial deposits at the surface.

 
diamond cut PDF Print E-mail
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Tuesday, 18 September 2007
diamond cut. A term used by some

lapidaries to mean brilliant cut. It is often applied to the brilliant cutting of Gemstones other than diamond. diamond cutter. (1) A general term for any workman engaged in the cut­ting and polishing of Diamonds. (2) One who rounds up rough as a step in the fashioning of brilliants. See

CUTTING, GIRDLING.

Diamond Dealers' Club, Inc. A non­profit trading association in New York City composed of diamond im­porters, wholesalers and cutters. Diamond Development Co. of Ghana. One of the companies in Accra, Ghana, that is licensed by the government of that country to buy diamonds from native miners. See

GHANA.

diamond diadem. A crown set with diamonds.

diamond doublet. An infrequently encountered assembled stone, con­sisting either of a diamond crown and a pavilion of another colorless material or two pieces of diamond cemented together. See doublet.

 
Diamond Corporation PDF Print E-mail
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Tuesday, 18 September 2007

diamond Corporation, Ltd. The

market-control organization of the diamond industry. It was organized in 1930, the successor to earlier diamond-purchasing and diamond-marketing syndicates, to purchase the output of the Diamond Produc­ers' Association on a quota basis and to arrange contractual purchase ag­reements with other producers. In­dustrial Distributors (Sales), Ltd., is confined to the marketing of crush­ing bort and drilling Diamonds; all other diamonds are marketed through the Diamond Trading Co., Ltd. The Corporation is owned about 80% by De Beers Consolidated Diamond Mines of South-West Af­rica, Ltd., and about 20% by its sub­sidiary, Consolidated Diamond Mines of South-West africa, Ltd.

Diamond Corporation (Sierra Leone), Ltd. A licensed diamond dealer in Sierra Leone, operating in the Bo and Yengema areas. It is a subsidiary of the Diamond Corpora­tion, Ltd., of London. See sierra leone.

 
Diamond Corporation Cote D'lvoire, Ltd PDF Print E-mail
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Tuesday, 18 September 2007

diamond Corporation Cote D'lvoire, Ltd. A subsidiary of the Diamond Corporation, Ltd., formed in 1961. The company has been granted a license to buy Diamonds on the open market at Abidjan, in the Ivory Coast. See diamond corpora­tion, LTD., IVORY COAST,

 
diamond cement PDF Print E-mail
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Tuesday, 18 September 2007

diamond cement. A cement used for setting Diamonds, such as a solution of mastic and isinglass in alcohol. Different kinds of cement are used for cleaving, sawing and polishing.

Diamond Club. A wholesale dia­mond exchange dealing chiefly in


rough materials (crystals). A tradi­tional marketing channel where wholesalers distribute rough to buyers. Found in the major diamond trading centers of the world; the or­ganizational structure is similar to the Diamond Bourse. See diamond bourse.

 
diamond artist diamond balance Diamond Bourse PDF Print E-mail
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Tuesday, 18 September 2007

diamond "artist." A person who is skilled in the illicit art of coating or painting Diamonds. See coated dia­mond.

diamond balance. A sensitive scale for weighing diamonds and other Gemstones. It is also used for obtain­ing the specific gravity of diamonds and other gemstones by the use of the hydrostatic weighing method. See hydrostatic weighing method, specific gravity, specific-gravity attachments.


Diamond Bourse. A wholesale diamond exchange dealing mainly in polished stones. Bourses are an an­cient marketing structure established in the major diamond trading centers such as Amsterdam, Antwerp, Lon­don, New York, Tel Aviv, and else­where. Buyers, sellers, and brokers sit across rectangular tables in a large room with long windows which face away from the sun and examine stones in natural daylight. After the stones have been studied, bargaining begins until a price is reached. Accurate balances are a-vailable for official weighing. Each acknowledged bourse belongs to the World Federation of Diamond Bourses which strictly enforces the rules of the trade since both buyers and sellers depend upon verbal ag­reements, credit, and mutual trust. Disputes are handled by a Board of Arbitrators. See diamond club.

 
diamond anniversary PDF Print E-mail
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Tuesday, 18 September 2007

diamond anniversary. An anniver­sary celebrated upon the completion of 60 (or sometimes 75) years follow­ing the event commemorated.

Diamond Area No. 1. The official name for the entire mining area in South-West africa that is under lease to Consolidated Diamond Mines of South-West Africa, Ltd. It is a strip of land that extends from the north bank of the Orange River north to latitude 26 degrees, a distance of ap­proximately 240 miles. Low tide of the Atlantic Ocean forms the western boundary, and the eastern boundary runs roughly parallel to the coastline and approximately 50 miles inland. Although Diamonds are known to occur all along this coastline, the main deposits are within the first 55 miles northwest of the Orange River and some are one to two miles in­land. See SOUTH-WEST AFRICA, CONSOLI­DATED DIAMOND MINES OF SOUTH-WEST AFRICA, LTD.

 
diamond-angle PDF Print E-mail
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Tuesday, 18 September 2007

diamond-angle (or bezel-angle) gauge. A gauge that measures the comparative correctness of the an­gles for the slope of the bezel facets in relation to the table of a fashioned diamond. Also used for other angles such as pavilion facets, nd girdles of emerald cuts.

 
diamond PDF Print E-mail
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Tuesday, 18 September 2007

diamond. The name is derived from the old French diamant. A mineral composed essentially of carbon that crystallizes in the cubic, or isometric crystal system. It is by far the hardest of all known natural substances (10 on Mohs scale); only manmade Borazon is reported as hard. In its transparent form, it is the most cherished and highly valued gem-stone. It occurs in colors ranging from colorless to yellow, brown, orange, green, blue and violet, black and pink. Reddish stones are known, but pure red Diamonds are extremely rare. Its hardness and high refrac­tive index (2.417) permit it to be fashioned as the most brilliant of gems, and its dispersion (.044) pro­duces a high degree of fire. The specific gravity is 3.52. Sources in­clude various sections of south, southwest and middle africa; cen­tral, east and northeast South America; India, Borneo, Australia and U.S.S.R. It is also found in the United States, but not in commercial quantity. (See individual entries for a more complete discussion of proper­ties, characteristics, sources, etc

 
De Young Diamond PDF Print E-mail
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Tuesday, 18 September 2007

De Young diamond. A 2.9-carat pink diamond in the Smithsonian In­stitution.

Dia-Bud. Trade name for man-made yttrium aluminum garnet (YAC). Diagem. Trade name for man-made strontium titanate.

Diamang. See companhia de diamantes

DE ANGOLA.

Diamanite. Trade name for man-made yttrium aluminum garnet (YAG).

diamant. French, German and Dutch for diamond.

Diamant. An illustrated magazine for diamond news, published monthly in Antwerp, Belgium.

diamantaire. French. As a noun, meaning diamond cutter or seller.

diamantband. German, meaning dia­mond bracelet, diamond necklace.


diamantbort. German, meaning diamond dust.

diamantbrillantieren. German, mean­ing to brillianteer a diamond.

diamant brut. French, meaning rough diamond.

Diamant Coeur. A heart-shaped stone of 12.33 carats, reportedly auc­tioned at Paris in 1933. No further details known.

diamant de premiere eau. French, meaning diamond of the first water. diamant de vitrier. French, meaning glazier's diamond.

diamante. Spanish, Italian and Por­tuguese, meaning diamond.

diamante en bruto. Spanish, mean­ing rough diamond.

diamante negro. Spanish, meaning carbonado.

diamantengrube. German, meaning diamond mine.

diamantenstaub. German, meaning diamond powder.

diamanter. French. As a verb, mean­ing to set with Diamonds or to make shine like a diamond.

diamantfarbe. German, meaning a diamond color.

Diamantfontein. A minor alluvial diamond deposit in the Schweizer Reneke area, Transvaal Province, Republic of South africa. diamantformig. German, meaning diamondlike shape

. diamantifere. French, meaning dia-mantiferous, or diamond bearing. diamantifero. Spanish, meaning dia-mantiferous, or diamond bearing.

diamantiferous (dye'-ah-man-tif-er-us). Diamond-bearing ground or rock.


Diamantina (dye'-ah-man-teen"-ah).

The name of a town and district in northeastern Minas Gerais, the site of the first discovery of diamonds in Brazil.

diamantinas. A little-used term that refers to diamonds of inferior color grade. The name is derived from the character of the majority of the stones from the Diamantina district, Minas Gerais, Brazil.

diamantista. Spanish, meaning dia­mond cutter.

diamantkette. German, meaning dia­mond chain.

diamantknopf. German, meaningd/a-mond button.

diamantnadel. German, meaning dia­mond pin.

diamantoid. Like, or of the nature of, diamond.

diamantschleifer. German, meaning diamond cutter.

diamantschmuck. German, meaning ornamented with diamonds.

diamant taille'. French, meaning cut diamond.

diamantwerker. Dutch, meaning dia­mond worker.

Diamite. Trade name for man-made yttrium aluminum garnet (YAG). Diamogem. Trade name for man-made yttrium aluminum garnet (YAG).

DiamoLite (trademark, Gemological Institute of America). Another name for DiamondLite.

Diamonair. Trade name for man-made yttrium aluminum garnet (YAG).

Diamonaura. Trade name for man-made yttrium aluminate.



 
Des Beiges Diamond PDF Print E-mail
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Tuesday, 18 September 2007

Des Beiges diamond. See queen of

BELGIUM DIAMOND.

De Valera. A minor alluvial diamond deposit in the Kimberley area, Cape Province, Republic of South africa. Annual production from these dig­gings is insignificant.

Dewey Diamond. The Dewey was one of the first diamond discoveries in the United States. It was a well-formed but poor-quality 23.75-carat octahedron that was found in 1884 by a workman, Benjamin Moore, at Manchester, Virginia. Although Moore placed an arbitrary value of $4000 on the stone, he sold it to Captain Samuel W. Dewey, a ge­ologist and mineralogist, for a re­ported $1500; he called it the Or-i-Noor, or Sun of Light. After being on exhibit at the New York City jewelry firm of Ball, Black & Co., it was cut into an 11.15-carat stone by Henry D. Morse, a Boston diamond cutter, at an additional cost of $1500. Cap­tain Dewey had glass replicas made of both the rough and the cut stone and sent them to the U.S. Mint in Philadelphia, the Peabody Museum of Natural History at Yale University, and the Smithsonian Institution in Washington, D.C. Eventually, Dewey had to mortgage the diamond and was unable to redeem it. It then be­came the property of a J. Anglist, who, in turn, mortgaged it for $6000 to John Morrissey, a pugilist, gambler and politician. Since Morrissey's death in 1878, the whereabouts of this stone has been unknown. Alter­nate name: Morrissey Diamond.

 
depth percentage PDF Print E-mail
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Tuesday, 18 September 2007

depth percentage. The depth of a stone measured from the table to the culet, expressed as a percentage of the stone's diameter at the girdle, is a relationship used in the analysis of the proportions of a fashioned diamond. In cuts with other than a round girdle, the narrowest girdle diameter is used. See fisheye, flat

STONE, LUMPY STONE, SHALLOW STONE, NAR­ROW CROSS SECTION.

 
De Park PDF Print E-mail
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Tuesday, 18 September 2007

De Park. A minor alluvial diamond deposit in the Schweizer Reneke area, Transvaal Province, Republic of South africa. This digging makes a very insignificant contribution to to­tal South African alluvial production. De Pohl Diamond. See pohl diamond deproclaimed area. A term used in South Africa for government-controlled alluvial diamond-bearing claims or lands on which mining has been suspended because of the claim-holders' failure to finance or work the property to the govern­ment's satisfaction. See proclaimed area, restricted alluvial digging.

 
De Kalk farm PDF Print E-mail
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Tuesday, 18 September 2007

De Kalk farm. Site of the first authen­ticated diamond find in africa. Orig­inally the stone was discovered by children (Erasmus Jacobs and Klon-kie, a young Hottentot shepherd) working and playing on the De Kalk farm on the Orange River in 1866. Eventually, Schalk van Niekerk "re­discovered" it next to the Jacobs' house where the children left it. He recognized it as a diamond crystal and it was later called the Eureka Diamond of 21 carats. See van niekerk. Delport's Hope. One of the early diamond diggings on the Vaal River, Cape Province, Republic of South Af­rica. Now an insignificant producer. Demidoff Diamond. A name used for the Sancy Diamond at one period during the 19th century when the stone was in the possession of the Demidoff family, in Russia. See sancy diamond.

 
de Boot, A. Boetius PDF Print E-mail
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Tuesday, 18 September 2007

de Boot, A. Boetius. diamond expert from Bruges, Belgium, and personal physician to the German Emperor Rudolph II. Author of Gemmarum et Lapidum Historia, 1604, which de­scribes and illustrates the early dia­mond cutter's equipment. A prime source for the early history of dia­mond cutting.

Deepdene Diamond. Many visitors to the famous Museum of the Philadelphia Academy of Sciences will surely remember the diamond that was the highpoint of the impres­sive collection: the 104.88-carat Deepdene. On loan for many years from Cary W. Bok of the founding family of Curtis Publications, this cushion-cut, golden-yellow diamond was named after the estate of Mrs. Bok's family. About 1954, the stone was purchased by an unknown New York City diamond dealer, who sold it to an undisclosed buyer. In 1971, a diamond called Deepdene and weighing 104.52 carats was auc­tioned at Christie's in Geneva. Sub­sequent gemological investigation proved this diamond to be artificially colored. Alternate spelling: Deep-deen.

Deep Fountain Diamond. A diamond named the Deep Fountain, valued at approximately $16,000, was reportedly stolen from the wife of a wealthy Indian industrialist in 1955. The international gang sus­pected of the theft may have been headquartered in London or Paris. Nothing more is known about this stone.

deep pavilion. See dark center,- pavilion depth.

 
De Beer BEERS MINES, KIMBERLEY MINES. PDF Print E-mail
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Tuesday, 18 September 2007

De Beer, D. A. and J. N. Brothers who bought the Vooruitzicht farm near Bultfontein for £50 and sold it for £6,300 after Diamonds were dis­covered there in May, 1871. The pipe became known as the De Beers Mine Pipe and over £590 million worth of diamonds have been found. Their name, De Beer, became famous and synonymous with diamond. See de

BEERS MINES, KIMBERLEY MINES.

De Beers Diamond. A 234.50-carat stone was cut from this 428.5-carat yellow octahedron discovered in the De Beers Mine, Republic of South africa, in 1888. The diamond was later sold to an Indian prince. Sub­sequent history and location un­known.

De Beers Mine. A diamond pipe mine that was discovered in South Africa in 1871 on a farm owned by D. A. and J. N. De Beer. It ceased operation in 1908. It was in this mine that events took place leading to the


formation of De Beers Consolidated Mines, Ltd. In 1873, Cecil Rhodes had amalgamated his claims with others and in 1880 formed the De Beers Mining Co. By 1885, it had be­come the leading company within the De Beers Mine, and by 1887 it had become the sole owner of the mine. In the following year, De Beers Consolidated Mines, Ltd., was regis­tered in Kimberley, as a result of the amalgamation of this mine and the Kimberley Mine. From 1888 until the mine closed in 1908, 40,000,000 tons of blueground were excavated and 23,201,719 carats recovered. The property was reopened in 1961 for eventual full-scale production. De Beers Mines. (1) The Bultfontein, De Beers, Dutoitspan, Kimberley and Wesselton diamond pipe mines. See kimberley mines, Bic five. (2) Sometimes used to refer to all diamond-mining properties owned or controlled by De Beers Consolidated Mines, Ltd.

De Beers New Rush. See kimberley mine.

De Beers Prospecting (Rhodesian Areas), Ltd. A company formed in 1955 to undertake diamond pros­pecting in Rhodesia.

De Beers Prospecting (S.A.), Ltd. A company formed in 1955 to under­take diamond prospecting in South Africa.

 
De Beers Consolidated Mines PDF Print E-mail
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Tuesday, 18 September 2007

. De Beers Consolidated Mines, Ltd. This company is the major factor in the diamond industry, because it holds a controlling interest in a number of diamond-mining com­panies and in companies having buy­ing contracts with independent pro­ducers. It owns or controls all of the important pipe mines in the Republic of South africa, including Premier, Jagersfontein, Wesselton, Bultfontein and Dutoitspan. Williamson Dia­monds, Ltd., in Tanzania is owned by De Beers and the government of that country on an equal ba­sis. Diamond-mining companies still retaining corporate existence but controlled by De Beers are the Pre­mier (Transvaal) Diamond-Mining Co. (Pty.), Ltd.; Consolidated Dia­mond Mines of South-West Africa (Pty.), Ltd.; Griqualand West Diamond-Mining Co.; Dutoitspan

 
Dauphine Diamond PDF Print E-mail
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Tuesday, 18 September 2007

Dauphine diamond (doe-fe-nay"). A misnomer for rock crystal from the French Alps.

Dayarai Diamond. A diamond of unknown weight and origin. Repor­tedly brought to the U.S. in 1921 by a Princess Fatima, a Sultana of the Af­ghan royal family, who claimed she had inherited it from her late father, Yakub Khan. She and her three sons arrived in New York City with the diamond at precisely the time that a mission from the new Afghan king was making a plea for U.S. recognition of that country. The diamond was sold at auction in New York to an undisclosed buyer for $5,000, probably in 1922. The $5,000 paid the Sultana's debts and the duty on the stone.

D.C. A trade abbreviation meaning diamond cut or brilliant cut

 
Darya-i-Nur Diamond PDF Print E-mail
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Tuesday, 18 September 2007
Darya-i-Nur diamond (Dacca). This square-cut 150-carat (estimated) diamond should not be confused with the 176-carat (estimated) pink Darya-i-Nur among the Iranian Crown Jewels. It was shown by the East India Company at the Crystal Palace Exhibition of 1851. Later it was reportedly sold to the Nawab of Dacca (East Pakistan). Its present whereabouts is not known. Alternate name: Darya-i-Nur (Dacca).
 
Darya-i-Nur Diamond PDF Print E-mail
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Tuesday, 18 September 2007

Darya-i-Nur diamond (Iran). Con­sidered to be the most celebrated dia­mond in the Iranian Crown Jewels and one of the oldest known to man, the 176-carat (estimated) Darya-i-Nur (Iran) is a crudely fashioned pale pink stone measuring one and one-half inches long, one inch wide and three-eighths of an inch thick. The name means Sea of Light, River of Light or Ocean of Light. Both the Darya-i-Nur and the historic Koh-i-Noor are said to have been in the possession of the first Mogul emperor of India, from whom they descended to Mohammed Shah. When the latter was defeated by Persia's Nadir Shah during-the sack of Delhi in 1739, he surrendered all his chief valuables, including the Diamonds and the well-known Peacock Throne. After Nadir's assassination in 1741, the Darya-i-Nur was inherited by his grandson, Shah Rokh. Later, it de­scended in succession to Mirza-Alam Khan Khozeime and thence to Mohammed Hassan Khan Qajar. Fi­nally, it came into the possession of Lotf-Ali Khan Zand, who was de­feated by Aga Mohammed Khan Qajar. In 1797, Aga Mohammed was succeeded by his grandson, Fath Ali Shah, who was both a collector and connoisseur of gems and whose name is engraved on one side of the great diamond. In 1827, Sir John Malcolm, a British emissary to the Persian Court and author of Sketches of Persia, described the Darya-i-Nur and the Taj-e-Mah (another famous diamond in the Persian Regalia) as the principal stones in a pair ofbracelets valued at one million pounds sterling. During the reign of the next shah, Nasser-ed-Din (1831-96), the stone was mounted in an elaborate frame, which is sur­mounted by the Lion and Sun (the emblem of the Imperial Government of Iran) and set with 457 diamonds and four rubies. It is still mounted in the same frame today. Although some researchers contend that the Darya-i-Nur was acquired by the East India Co. and exhibited at Lon­don's Crystal Palace Exposition in 1851, Iranian officials at the Central Bank of Iran in Tehran, where the Crown Jewels are kept, told the Gemological Institute of America in 1964 that it has never left the Trea­sure Vaults. In 1906, Mohammed Ali Shah, after being defeated by the Constitutionalists while carrying the diamond and other valuables withhim during the Persian Revolution, took refuge in the Russian Legation and claimed that the Jewels were his personal property. However, as a re­sult of intense efforts made by the freedom fighters, this priceless token of Nadir's conquests was restored to the country. Today, the Darya-i-Nur holds a prominent place among the Iranian Crown Jewels. The Iranian Crown Jewels were studied and au­thenticated in 1966 by the late Dr. V. B. Meen of the Royal Ontario Museum. It is now believed that the Darya-i-Nur is the major portion of Tavernier's Great Table. Alternate spellings: Durria-i-Nur and Dariya-eye-Noor.

 
dark cape dark-field illumination PDF Print E-mail
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Tuesday, 18 September 2007

dark cape. See cape dark center. The optical effect seen in round brilliant-cut Diamonds di­rectly related to pavilion depth. It is the result of massive unplanned light leakage with the dark center first be­coming noticeable at about 45% pavilion depth when viewed through the crown. The optimum pavilion depth is 43.1% which, when ex­ceeded, causes the area of the table to lose brilliance and become com­pletely dark at a pavilion depth of 49 to 50%. See pavilion depth, table reflec­tion.

dark-field illumination. A method of illuminating diamonds and other Gemstones with a strong light from the side while the stone is viewed against a black background. It causes inclusions and imperfections to stand out clearly and reduces confusing surface reflections. This principle, together with light-field illumination, is incorporated in the Cemolite, or Cemscope (trademark, Gemologi-



Last Updated ( Tuesday, 18 September 2007 )
 
Dar-Challa Darcy Vargas Diamond PDF Print E-mail
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Tuesday, 18 September 2007

Dar-Challa. A subsidiary of Com-pagnie Miniere c/e I'Oubangui Orien­tal, one of the principal diamond-mining companies in the Central Af­rican Republic. See west oubancui.

Darcy Vargas Diamond. A 460-carat brown diamond found in the Coromandel district, Minas Cerais, Brazil, 1939. Named for the wife of Cetulio Vargas, the then Brazilian president. It was displayed at Savitt Jewelers, New Haven, Connecticut, in the early 1940's. Ultimate disposi­tion unknown. (See" photo.)

 
damage blemish PDF Print E-mail
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Tuesday, 18 September 2007

damage blemish. (1) A blemish other than one inherent in the stone at the time of cutting. (2) Usually a surface or near surface clarity imperfection developed during or after the stone is cut, e.g., nicks, chips, scratches, per­cussion marks, etc.

Damage Report. Written report by qualified gemologists or gemological laboratories giving results of a labo­ratory examination under high mag­nification. It determines the nature and extent of damage, if any, and whether or not it existed at the time the stone was last polished. Almost all insurance settlements require a damage report.

Dan Campbell diamond. Found on the Vaal River, Cape Province, Re­public of South africa, in 1916. 192.50 carats. Present location un­known.

Last Updated ( Tuesday, 18 September 2007 )
 
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