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Orapa Pipe & Diamond Mine Orchid Diamond wholesaler O'Reilly Diamond PDF Print E-mail
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Sunday, 23 September 2007

Orapa Pipe & diamond Mine. Orapa pipe formerly designated 2125, second largest diamond pipe.

Orchid diamond. Described as hav­ing a "pink-lavender color," this 30.45-carat crystal was imported in 1935 by Lazare Kaplan & Sons, Inc., New York City diamond cutters, who fashioned it into a 9.93-carat em­erald cut. This rare-colored gem was exhibited in museums in Boston and Cleveland and was sold in 1940 to a private buyer through a


wholesaler. One overly poetic gen­tleman once described it as "contain­ing all the color of a mile of tropical sunset." In 1965 it was reported to have changed hands, but the present owner is unknown. Oregon diamond. A 3.87-carat, grayish-green distorted octahedron. Found in 1893 near Oregon, Dane Co., Wisconsin. Purchased by Tiffany & Co. for $50 and presented to American Museum of Natural His-


tory, New York City. It was stolen from the Museum and never recov­ered.

O'Reilly diamond. See eureka dia­mond.

O'Reilly, John. Came hunter and trader in the old British Cape Colony which is now known as the Republic of South Africa. Van Niekerk en­trusted a stone found by Erasmus Jacobs to O'Reilly in 1867 to have it examined at Colesberg. The stone proved to be a 21.25-carat diamond which made African Diamonds known to the world and initiated fur­ther development of the great dia­mond fields of South Africa. This was the first authenticated diamond find in South Africa. It was later cut to a 10.73-carat brilliant and named the Eureka diamond. See eureka diamond.

Oriental diamond. An obsolete term that was once used to distinguish In­dian from Brazilian Diamonds after the discovery of Brazilian deposits and while Indian stones were still a factor in the market.

original lot. An unsorted lot of rough Diamonds sold by the diamond Trad­ing Co. See lot.

 
optical density optical separator orange Orange River Oranjemund PDF Print E-mail
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Sunday, 23 September 2007

optical density. See optically dense, re-

I RACTIVE INDEX.

optical separator. A device devel­oped by the diamond Research Lab­oratory, Johannesburg, Republic of South Africa, for the recovery of Diamonds from worthless material. It is based on the difference between the light-reflecting properties of dia­monds and other gravel constituents.

See diamond RESEARCH LABORATORY.

orange

diamond. A diamond of a distinct orange tint. It does not refer to a diamond from the Orange River Valley, although most stones of this color are found in the Republic of South Africa. Many of them are red­dish orange-brown, somewhat simi­lar to the color of some zircons. Others are a more vivid reddish-orange color, reminiscent of flame spinel. Some vivid deep-orange dia­monds have been found in the Wes-selton Mine. Few of these Diamonds reach the North American trade. They are properly called fancies.

Orange Free State. A province in the Republic of South Africa, south of the Transvaal, that was formerly a vir­tually independent colony of Boers. Some important diamond mines, such as Jagersfontein and Koffiefon-tein, are located in the province. Al­luvial production from the Orange Free State has practically ceased, however.

Orange River. The principal river in the Republic of South Africa along


which, together with its main tribu­tary, the Vaal, are located many of the country's alluvial diamond depos­its. It forms the boundary between South-West Africa and the Republic of South Africa, and rises in Lesotho (formerly Basutoland). The first large white rough diamond, the 83.50 carat Star of South Africa or Dudley diamond, found in the Orange River, was fashioned into a 47.75-carat oval brilliant.

Orange Tiffany diamond. See tiffany

diamond.

Oranjemund. A town about five miles north of the mouth of the Or­ange River that is maintained by Consolidated diamond Mines of South-West Africa, Ltd., for its em­ployees. Important mining activity is carried out not far to the north. See

SOUTH-WEST AFRICA.

Orapa pipe. The world's second largest known kimberlite pipe, de­signated 2125 AK/1. It is part of the Letlhkane group of kimberlites, lo­cated in the area of Orapa on the eastern edge of the Kalahari desert, about 210 miles north of Gaborone, the capital of Botswana. The Orapa pipe was discovered by the De Beers prospecting team, in 1967, under the sands and gravels of the Kalahari desert. Officially opened on May 26, 1971, it came into production July 1, 1971. It is oval in plain view, 1.2 km. x 1.61 km., with a surface area of 113 hectares (280 acres), and re­ported to be about 5,000 feet deep. The preliminary assessments indicate a ratio of Gemstones to industrial Diamonds of 10 to 90, respectively. Ore reserves have been proven to 37 meters depth (about 120 feet) which

 
Oppenheimer, Harry Oppenheimer, Sir Phillip PDF Print E-mail
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Friday, 21 September 2007

Oppenheimer, Harry (1908- ).

Son of Sir Ernest Oppenheimer and successor, upon his father's death in 1957, to the chairmanship of De Beers Consolidated Mines, Ltd., Anglo-American Corporation, Ltd., and a number of other companies in the De Beers group. He has con­tinued this work with notable suc­cess, bringing into the De Beers fam­ily, in partnership with the Govern­ment of Tanzania, the Williamson diamond Mine and initiated the marketing of Russian Diamonds with Soviet authorities outside the Soviet bloc through the Central Selling Or­ganization. Greater stability has also been achieved for the diamond in­dustry in Sierra Leone. See op­penheimer, SIR ERNEST.

Oppenheimer, Sir Phillip (1911- ).

Nephew of the late Sir Ernest Op­penheimer. Managing director of the


Central Selling Organization in Lon­don and director of the Anglo-American Corporation and De Beers Consolidated Mines, Ltd.

Oppenheimer Student Collection. A

collection of more than 1500 carats of rough gem and industrial dia­monds that was presented to the Gemological Institute of America in


1955 by the diamond Corporation, Ltd., through the good offices of the late Sir Ernest Oppenheimer, Chair­man of the Board of the Corpora­tion, for educational and instruction­al purposes. optical density. See optically dense, re-

I RACTIVE INDEX.

 
Oppenheimer, Sir Ernest PDF Print E-mail
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Friday, 21 September 2007

Oppenheimer, Sir Ernest (1880-

1957). Sir Ernest Oppenheimer, who later became universally known as "the King of Diamonds," was born in Freiberg, Germany, in 1880. He started his illustrious career in the diamond industry in 1896, at the age of sixteen, when he joined the London diamond firm of Anton Dun-kelsbuhler & Co. as a sorter and grader. He soon gained a reputation for proficiency, and in 1902, at the age of twenty-two, Dunkelsbuhler's sent him to their office in Kimberley, South Africa, where they needed competent graders. In 1917, he joined an American consulting en­gineer for a gold-mining company


and organized the Anglo-American Corporation of South Africa, Ltd., which was a success from the start. The gold fields in which they held interests were so productive and profitable that Oppenheimer, who had become chairman of Anglo-American, began searching for further opportunities. Keenly aware of the potentialities of the diamond fields of South-West Africa, he bought up mines formerly owned by Germans after the war and amalga­mated them under Consolidated diamond Mines of South-West Af­rica, Ltd., in which Anglo-American held a controlling interest. This act made him an important figure in the diamond-producing world. Within a year, Consolidated Mines was ac­counting for one-fifth of all the dia­monds mined in Africa. In 1926, Sir Ernest was appointed a director of De Beers; later he became chairman. He had De Beers buy out Anglo-American's interest in Consolidated. Then, he set up a firm called the diamond Corporation, Ltd., through which almost all of the world's dia­monds were sold, and the prices regulated. In 1933, he organized a subsidiary firm called the diamond Trading Co., Ltd., to serve as the sole channel through which the diamond producers sold their stocks of gem Diamonds. At the time of his death, on November 25, 1957, Oppen­heimer was a director of 41 com­panies and the chairman of 28 others, including Anglo-American Corporation of South Africa, Ltd., De Beers Consolidated Mines, Ltd., Consolidated diamond Mines of South-West Africa, Ltd., the Dia­mond Corporation Ltd., and Premier

 
old-miner onza para diamantes CULET, BRILLIANT CUTopen setting PDF Print E-mail
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Friday, 21 September 2007

old-miner. An abbreviated form of old-mine cut diamond.

old single cut. A simple form of bril­liant cutting that has a octagonal-shaped girdle outline, a table, 8 bezel facets, 8 pavilion facets, and sometimes a culet. Used for small Diamonds.

Ombelle M'Poko. A minor dia­mond-mining area in the Central African Republic.

one-grainer. See grainer.

onza para diamantes. Spanish, meaning the diamond ounce. Equal to 431.42 English grains.

onzuiver. A Dutch word meaning impure. It is used by some diamond men to refer to an imperfect dia­mond.

open cast mining. Surface mining, in which the ore (diamond for exam­ple) is exposed to the sky by remov­ing the overburden. All pipe mines are first worked from the top down­ward by this systematized method. The Finsch Mine is an excellent ex­ample of the open cast method of mining.

open culet. A culet that is larger than necessary; usually, one that is visible to the unaided eye. It may be de­scribed as medium, large or very large. See culet, closed culet, off-center

CULET, BRILLIANT CUT (ROUND). (See photo.)

opening a diamond. In the dia­mond-cutting industry, a trade term used to describe the operation of polishing a facet, or "window," on the surface of a heavily coated or rough-surfaced diamond, so that a clear view of the interior can be had


by the cutter before proceeding with the work. A window must be ori­ented properly, so as to eliminate dis­tortion caused by refraction of light.

open setting. A stone setting in which the mounting holds a stone with the pavilion facets open to the light; effectively used with transpa­rent stones, especially diamond.

open table. A term that is sometimes used to refer to the table on a spread, or swindled, stone. To some, any table diameter of 60% or more of the girdle diameter is open; to others, open means 65% or more. See table;

TABLE SIZE; SPREAD STONE; SWINDLED STONE; PROPORTIONS, GOOD.

Oppenheimer diamond. In 1964, Dutoitspan, the famed mine near Kimberley, South Africa, was the site of discovery of a large, pale-yellow octahedron. The Oppenheimer has only a few small black inclusions and is transparent and unusually well formed. It measures about 1% x VA inches and weighs 253.70 carats. In the same year, the owner, Harry Winston, New York City gem mer­chant, donated the superb crystal to the Smithsonian Institution,


Washington, D.C., in memory of Sir Ernest Oppenheimer, late Chairman of the Board of De Beers Consoli­dated Mines, Ltd. In 1971, it was dis­played at the "De Beers Hall" of the mining museum in Kimberley, Re­public of South Africa. Alternate name: Dutoitspan diamond.

 
off-center table Offin River Estates oitava old-mine cut PDF Print E-mail
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Friday, 21 September 2007

off-center table. Distorted rough is sometimes cut in a manner that places the table nearer to the girdle at one point than elsewhere. It is the result of the opposite crown facets being cut at different angles. May also be off-center because opposing bezels are of different sizes. An off-center table may be inclined to the girdle plane, but usually it is parallel

tO it. See TABLE, TABLE SIZE, SYMMETRY.

off-color diamond. (1) In the Ameri­can trade, any diamond that has a tinge of undesirable color, especially yellowish or brownish, that is easily apparent to the unaided but prac­ticed eye without comparison with a stone of known color. (2) A term that has been used at the South African diamond mines for the grade of rough Diamonds below the cape and bye grades.

Offin River Estates, Ltd. A small diamond-mining company that works alluvial deposits in the Birim River Valley, Oda district, Ghana (Gold Coast). Production is not great. See ghana.

oilie. (1) In the American diamond trade, a little-used term that is synonymous with Premier diamond. (2) In some European countries, the term applies to a diamond having a blue-green tint. See premier diamond.

oil stones. A term used by South Af­rican miners for agates found asso-


ciated with Diamonds in the alluvial diamond deposits.

oitava (or octavo). A Brazilian weight for Diamonds and other gems; the equivalent of about \7Vi carats. Oktyabrksy diamond. One of the many large (weight unreported) named rough diamond crystals in the Russian diamond Fund at the Krem­lin.

old-English cut. Same as single cut. old-European cut. A term applied to the earliest form of circular-girdled full brilliant. It is characterized by a very small table, a heavy crown, and great overall depth. Improperly refer­red to as old-mine cut.

Old-European cut

Old-Mine cut


old-mine cut. (1) A trade term that is applied properly to an early form of brilliant cut with a nearly square or cushion-shaped girdle outline. (2) A term applied occasionally and incor­rectly to a somewhat more modern style of brilliant cut that also has a much higher crown and smaller table than the modern brilliant cut, but whose girdle outline is circular or approximately circular a style of cutting that is more properly call-

 
oblong cut octagon cut cubic, or isometric, crystal system PDF Print E-mail
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Friday, 21 September 2007

oblong cut. Same as emerald cut. Occidental diamond. A misnomer for rock crystal.

Ocean of Light diamond. See darya

l-NUR diamond.

octagon cut. An octagonal (eight-sided) form of cutting, usually step cut, the length and angles of the sides of which may vary.

octagon work. The operation of plac­ing the eight main facets on the crown and pavilion of a diamond, thus converting the table into an oc­tagon shape.

octahedral cleavage (ahk'-tah-he"-dral). Cleavage parallel to any of the four pairs of faces of the octahedron.

See OCTAHEDRON, CLEAVAGE, CLEAVAGE (IN diamond).

octahedron (ahk'-tah-he"-dron).

Octahedron


One of the seven basic (and the most common) forms in the highest sym­metry (hexoctahedral) class of the

cubic, or isometric, crystal system. It has eight equilateral, triangular faces, each of which intersects all three of the crystallographic axes at an equal distance from the center. See cubic

SYSTEM, HEXOCTAHEDRAL CLASS. (See

photos.)

octavo. Same as oitava.

Oda. The district in the Eastern Prov­ince of Ghana in which major dia­mond deposits are located. See

GHANA.

Oersonskraal. A minor alluvial dia­mond deposit in the Wolmaransstad area, Transvaal Province, Republic of South Africa. Approximately 700 carats were reported from this dig­ging during one recent year.

off-center culet. A culet that, due to differences in the angles of the op­posite pavilion facets, is off center with respect to the girdle outline. It usually results from repairing or re-


polishing a portion of the pavilion or from attempting to retain maximum weight from a distorted piece of rough. Off-center culets often result from pavilions at the same angles but of different sizes. See culet, closed

CULET, OPEN CULET, BRILLIANT CUT (ROUND).

 
nuclear reactor Nur-ud-Deen Nur-ul-Ain Diamond PDF Print E-mail
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Friday, 21 September 2007

nuclear reactor. A device by which a fission chain reaction can be in­itiated, maintained, and controlled. Its essential component is a core of fissionable fuel which usually has a moderator, a reflector, shielding, and a control mechanism. The nuclear radiation may take the form of gamma rays, or other nuclear parti­cles like alpha rays (helium nuclei), or beta rays (electrons). Neutrons, positrons, and protons also may be emitted along with the transmuta­tions. It is used to artificially color Diamonds. See cyclotron-treated dia­mond, PILE-TREATED diamond, TREATED DIA­MOND.

Nur-ud-Deen (Light of Faith) Dia­mond. A large (size unknown) pink diamond, mounted in the center of a cross, that belonged to Prince Alex­ander Tzary in the 19th century. The cross, which was embellished with 85 brilliants and 160 rose cuts, was sold in London, in 1898, for £750. No additional information is avail­able. Alternate spellings are Noor-un-Deen and Noor-ud-Deen.

Nur-ul-Ain diamond. A 60-carat pink diamond. Set in a diadem with 323 smaller Diamonds. Name means Light of the Eye. Belongs to Iranian Crown Jewels. Believed to have been cut from the Great Table. See darya-i-nur. Alternate spelling is Noor-ol-Ayn.

nyf. See naif.

 
Noor-ol-Ayn Diamond normal class North Star Diamond PDF Print E-mail
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Friday, 21 September 2007

Noor-ol-Ayn diamond. See nur-ul-deen diamond.

Noor-un-Deen diamond. See nur

UD-DEEN diamond.

normal. In the study of light, the NORMAL is an imaginary line drawn perpendicular to the surface of an optically dense medium. The NOR­MAL may be drawn through any given point on any surface to de­scribe the behavior of light at that


point. See diagrams, ancle of refrac-

IION, CRITICAL ANCLE, CRITICAL ANCLE CONE, IOTAL REFLECTION.

normal class. See hexoctahedral class.

"north light." The traditional light source used in color grading dia­monds. North skylight or "north light" is illumination from the north­ern sky between 10 a.m. and 12 noon on a moderately overcast morning during the spring or fall. Custom has it that light reflected from the north sky affords the least variation of intensity and color, is relatively shadow free, and contains Ihe least amount of ultraviolet. How­ever, north skylight is not sufficiently c onstant from day to day, at different limes of the day, or from one locality to another to be entirely satisfactory as a light source standard. Also, be­cause of the presence of ultraviolet in sunlight, the color of stones that fluoresce blue improves in daylight. Consequently, GIA has developed a lighting system that closely approxi­mates the desirable qualities of north skylight for diamond color grading. The closest approximation for a true color balanced daylight, as used in Ihe GIA system, has a correlated color temperature of 6200° Kelvin. See diamondlux, diamondlite.

North Star diamond. A fancy 32.41-carat blue pear-shape cut from a 97-carat rough found in the Ja-gersfontein Mine. Baumgold Broth­ers bought, cut and polished the rough valued at $300,000 in 1969. No other information is available.

Nova Estrela do Sul (New Star of the South) diamond. A 140-carat


greenish diamond that was found in 1937 in the Abaete River, Minas Gerais, Brazil. The present location of this stone is unknown.

 
Nier-Gem Niekerk, Schalk van. See eureka dia­mond PDF Print E-mail
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Friday, 21 September 2007

Niekerk, Schalk van. See eureka dia­mond, STAR OF SOUTH AFRICA diamond.

Niekerk's Hope. One of the early al­luvial diamond diggings on the Vaal River, Cape Province, Republic of South Africa.

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

nitrogen. Nonmetallic, colorless element symbol N, and a diatomic


gas (N2). Occurs as a trace element inclusion in the lattice in some dia­monds. Nitrogen occurs as aggregate in Type la or as dispersed-atoms in Type lb Diamonds. Nitrogen does not occur in Type II Diamonds. The pres­ence of nitrogen atoms dispersed through the crystal lattice in the order of one part in a million is be­lieved to cause the diamond to ab­sorb light in the blue region which

results in the yellowish-body color of Type I Diamonds. See type i diamond. Nizam (or Nizzam) diamond. An apparently unauthenticated stone thought to be in the treasury of the Nizam of Hyderabad (ancient Gol-conda) since before the Golconda diamond fields were exhausted. Some gem historians believe that it was found in Golconda's Kollur Mines about 1835. It was reported to have weighed either 440 or 340 carats in the rough and to have been broken during the Indian Mutiny in 1857. The Nizam may have been sold to an Indian banker for 70,000 rupees; at that time its value was placed at £ 200,000. After cutting, it was thought to have weighed 277 carats. Models made of it represent a concave-based, elongated, domed


stone covered with irregular, con­cave facets. Presumably, this great diamond has been owned by succes­sive generations of Hyderabad's rul­ers and retains this status today, al­though no confirmation has been made of this conjecture. The name is also sometimes spelled Nizzam.

Nizzam diamond. Same as Nizam diamond.

NMDC. See national mineral develop­ment CORPORATION.

Nooitgedacht. An alluvial diamond deposit near Barkly West, Cape Prov­ince, Republic of South Africa. Al­though owned by De Beers Consoli­dated Mines, Ltd., it is worked by private diggers. Recent annual pro­duction has been approximately 2000 carats.

Nooitgedacht diamond. The Noo­itgedacht yellow diamond rough weighing 325 carats was discovered by a native in the diggings at Noo­itgedacht, near Kimberley, Cape Province, Republic of South Africa, in 1953. The site had been dug for 22 years without success by its owner, Christoffel Boer. The diamond was sold by Boer for $38,000, and the discoverer was awarded $840. The disposition of the Nooitgedacht is not known.

 
Nepal Pink Diamond Nevada diamond New South Wale PDF Print E-mail
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Friday, 21 September 2007
Nepal Pink diamond. A stone re¬ported by a United States gem dealer, while in Nepal in 1959, as a 72-carat, old Indian cut, with a "soft, rose-pink" color. Further information lacking.
Netherlands Diamant-Speurwerk Centrum. A Dutch research center established in 1954 by the Amster¬dam Jewelers' Association for the purpose of carrying out investiga¬tions aimed at improving diamond cutting techniques and machines, and increasing the quality of the Netherlands product. Nevada black diamond. A misnomer for obsidian.
Nevada diamond. A misnomer for ar¬tificially decolorized obsidian.
New Eland Mine. A small diamond pipe mine in the Boshof area, Or¬ange Free State, Republic of South Africa.
New Jagersfontein Mining & Explo¬ration Co., Ltd. The company that owned the Jagersfontein Mine, in the district of Fauresmith, Orange Free State, Republic of South Africa. The mine was closed in 1971. The prop-

erty and plant were leased under an agreement to De Beers Consolidated Mines, Ltd. See JAGERSFONTEIN MINE.
New Rush. See KIMBERLEY MINE.
New South Wales. The principal diamond-producing State in Aus¬tralia. See AUSTRALIA.
New Star of the South diamond. See
NOVA ESTRELA DO SUL diamond.
New Thor Mine. A small diamond pipe mine in the Winburg area, Orange Free State, Republic of South Africa.
New Union Coldfields Group. A South African mining concern, of which Star Diamonds (Proprietary), Ltd., in the Orange Free State, is a subsidiary. See STAR Diamonds (PROPRIE¬TARY), LTD.
Ngelehun. The site of a rich alluvial diamond deposit that was reported in 1958 in Sierra Leone.
N'Gounie. An alluvial diamond de¬posit in Gabon that has been all but exhausted.
Niarchos diamond. A 426.50-carat flawless diamond of exceptionally fine color that was found in the Pre¬mier Mine, Republic of South Africa, in 1954. The late Sir Ernest Op-penheimer (Chairman of De Beers Consolidated Mines, Ltd., the owner of the Premier Mine), who had the rough in his personal collection for a short time, valued it at $300,000. In
1956, it was sold as part of an
$8,400,000 parcel to Harry Winston,
New York City gem dealer, who, in
1957, cut it into a 128.25-carat pear-
shaped brilliant with 58 facets on the
crown and pavilion and 86 addi¬
tional facets around the girdle. In the
same year, it was bought by Stavros
S. Niarchos, Greek ship-builder

and industrialist, for a reputed $2,000,000. A 30-carat marquise and a 40-carat emerald cut were also ob¬tained from the same rough. It was pictured in color in the April 1958 issue of National Geographic Magazine. Also known as the Ice Queen and the Pretoria diamond. nick. A minor chip out of the surface of a diamond, usually caused by a light blow. Nicks are more likely to be found along the girdle than elsewhere, although they may also appear along a facet junction or on a facet.
 
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