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DIAMOND R
river PDF Print E-mail
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Monday, 29 October 2007

river. (1) An early trade term still used by some dealers to designate the finest color grade of Diamonds; i.e., an extraordinarily transparent, colorless stone. For an approximate comparison of this grade to those used in the color-grading systems of the Gemological Institute of America and the American Gem Society, refer to chart in Appendix entitled, Com­parison of Several Different diamond Color-Grading Systems. (2) Any dia­mond found in an alluvial deposit.

See GIA COLOR-GRADING SYSTEM, AGS COLOR-GRADING SYSTEM, COLOR GRADE.

 
Rio das Velhas PDF Print E-mail
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Monday, 29 October 2007

Rio das Velhas. A river in Minas Gerais, Brazil, the gravels of which have yielded small quantities of dia­monds.

Rio das Velhas diamond. This large diamond of unknown weight was re­portedly found in the Rio das Velhas area of Minas Gerais, Brazil, in 1852. Nothing more is known about it.

Rio de Sao Francisco. A river in the Bagagem District, Minas Gerais, Brazil, the gravels of which have produced many Diamonds. See

BAGAGEM.

Rio Jequetinhonha. One of the prin­cipal diamond-producing rivers in the Diamantina District, Minas Gerais, Brazil.

 
Rietput Riggs Diamond PDF Print E-mail
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Monday, 29 October 2007

Rietput. A minor alluvial diamond deposit in the Schweizer Reneke area, Transvaal Province, Republic of South Africa. Annual production is negligible.

Riggs diamond. A 28.3-carat dia­mond in the Smithsonian Institution. Reported to be colorless.

Rio Belmonte. One of the principal diamond-producing rivers in the Diamantina District, Minas Gerais, Brazil.

Rio Branco. A minor diamond-producing state in Brazil. See brazil.
 
Rietkuil PDF Print E-mail
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Monday, 29 October 2007

Rietkuil. A minor alluvial diamond deposit in the Wolmaransstad area, Transvaal Province, Republic of South Africa. This mine produced approximately 300 carats during one 12-month period in the late 1950's.

 
relative PDF Print E-mail
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Monday, 29 October 2007

relative. The proportion of Diamonds to the amount of blue ground process­ed at the major South African pipe mines can be computed in carats per 100 loads of ore (a load is approxi­mately 4/5 of a short ton). In one year in the mid-1950's, for example, the number of carats produced per 100 loads by four of the principal mines was as follows: Wesselton, 18.50 carats; Bultfontein, 19.30 car­ats; Dutoitspan, 10.80 carats; Jagersfontein, 6.30 carats. Therefore, the average recovery for these mines was 13.725 carats per 100 loads of blue ground treated. Stated another way, it was about 0.16 carat per ton, or roughly one part diamond to 27,-000,000 parts of blue ground. The famous Premier Mine yielded 27.80 carats per 100 loads in the same year, but approximately 70% of the pro­duction was of industrial quality.

 
Richelieu Diamond PDF Print E-mail
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Monday, 29 October 2007
Richelieu diamond. A 19-carat heart-shaped diamond willed to the French Crown by Cardinal Richelieu, Chief Minister under Louis XIII and mentor of Cardinal Mazarin. It was reported to be "of very fine water" and Twinning stated that Queen Marie Leczinka, wife of Louis XV, probably wore a pair of earrings set with the Richelieu and three of the Mazarin Diamonds, number 4, 5 and 6. Since the great diamond robbery of 1792, the history of the Richelieu has been lost and its present where¬abouts is unknown.
 
rhomboid cut PDF Print E-mail
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Monday, 29 October 2007
rhomboid cut. A four-sided paral­lelogram-shaped form of cutting, usually step cut.

R.I. The abbreviation for refractive index.

Riccia diamond. A 15-carat rose-colored diamond owned by the Prince de la Riccia. No additional in­formation is available.

 
Rhodesia PDF Print E-mail
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Monday, 29 October 2007

Rhodesia. The Federation of Rhodesia and Nyasaland, an African country consisting of Northern and Southern Rhodesia and Nyasaland, has been an insignificant producer of Diamonds for many years. In 1908, it was prospected carefully for dia­monds and for a time a few hundred carats were found yearly, but none of the deposits ever proved payable and the search was abandoned. In­frequent organized prospecting ven­tures since 1908 have been no more successful. In 1955, however, De Beers Consolidated Mines, Ltd., re­newed its interest in this country and organized De Beers Prospecting (Rhodesian Areas), Ltd., to undertake further exploratory work in Northern Rhodesia. The diamond deposits are known as the Somabula field, and are located near Gwelo

 
Rhodes, Cecil John PDF Print E-mail
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Monday, 29 October 2007

Rhodes, Cecil John (1853-1902). En­glish colonial statesman and pioneer of diamond-market control in South Africa. In 1870, he went to South Af­rica for his health, joining an older brother in Natal. The brothers par­ticipated in the diamond rush in Griqualand West, in Cape Province, in 1871, and soon were among the most prosperous of the diggers. After a trip through the country, he con­ceived his idea of a United Empire under the British Crown, visualizing South Africa as a tremendous source of mineral wealth. Eventually, he succeeded in consolidating a number of claims within the De Beers Mine and formed the De Beers Mining Co., in 1888. The merger be­tween the Rhodes' and Barnato interests, which concerned the entire De Beers Mine and the greater part of the Kimberley Mine, led to the in­corporation of De Beers Consoli­dated Mines, Ltd., in the same year. Shortly afterwards, De Beers Consolidated Mines acquired a 100% interest in the Kimberley, Dutoitspan and Bultfontein Mines, thus gaining control of the diamond market and becoming the most influential factor in the industry. Rhodes became the first chairman of De Beers and held office until his death in 1902. Rhodesia was named in honor of him. See de beers consolidated mines,

LTD.; BARNATO, BARNETT.

 
Retail Jewelers of America PDF Print E-mail
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Monday, 29 October 2007

Retail Jewelers of America, Inc. Ab­breviated RJA. A national trade or­ganization that was formed in 1957 upon merger of the American Na­tional Retail jeweler's Association and the National jeweler's Associa­tion. The purpose of the organization is to promote the general welfare, and prosperity of the retail jewelry industry. Over 42 state jewelers' as­sociations are affiliated with the RJA; membership in a state association automatically establishes member­ship in the RJA, and vice versa, thus creating a national team of retail jewelers. The organization sponsors and manages two National Jewelry Trade Shows per year in New York City. Headquarters: 10 Rooney Cir­cle, West Orange, New Jersey 07052.

 
restricted alluvial digging PDF Print E-mail
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Monday, 29 October 2007

restricted alluvial digging. A term used in the Republic of South Africa for alluvial diamond diggings upon which the number of persons who can work each claim is restricted by the government. See proclaimed area, deproclaimed area.

 
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