Diamonddictionary.org

Russian diamond Fund. The official name of the vast collection of dia­monds and jewelry comprising the Russian Regalia and the Romanoff jewels which is housed in the Krem­lin, Moscow. Also known as the Rus­sian Treasury of Diamonds and Pre­cious Stones. The Diamonds alone in this vast collection reportedly weigh more than 25,300 carats, about 1500 carats of which are represented by 70 important gems, such as the Or-loff and the Shah. The best quality stones are of Indian origin, although some good ones are from Brazil and a few from South Africa. Russian Portrait diamond. See Rus­sian table portrait diamond.

Rossini Jewel. Trade name for man-made strontium titanate

. rotary washing pan. A device used to free Diamonds from soil, sands, gravel, or crushed ore by subjecting it to the action of water in order to extract by density differences the valuable material. The washing pan is an annular container, about 5 feet in diameter and about 10 inches deep. A vertical axle connected to the central hole has 4 crossed arms

Rose D'Angleterre diamond. A large (weight unknown) circular-shaped diamond that was bequeathed to Anne of Austria by Cardinal Mazarin after his death in 1661. Its later his­tory is unknown. See mazarin, cardinal

JULES.

rose recoupee. An alternate name for double-Dutch (or double-Holland) rose cut.

rosette. An alternate term for a rose-cut diamond. See rose cut rosie. An abbreviated term for a rose-cut diamond. See rose cut

rose cut (or rosette). An early style of cutting that is thought to have originated in India and to have been brought to Europe by the Venetians. In its most usual form, it has a base of one large flat facet and a somewhat dome-shaped top that is covered with a varied number of triangular facets and terminates in a point. The rose cut is now confined principally to small Diamonds. See common rose

CUT, THREE-FACET ROSE CUT, SIX-FACET ROSE CUT, ANTWERP (OR BRABANT) ROSE CUT, HALF-DUTCH (OR HALF-HOLLAND) ROSE CUT, FULL-DUTCH (OR FULL-HOLLAND) ROSE CUT, DOUBLE ROSE CUT ROSE RECOUPEE, BOAT-SHAPED ROSE CUT, PEAR-SHAPED ROSE CUT, CROSS-ROSE CUT, ROSE D'ANGLETERRE.

Rosa de Abaete diamond. Found in the Abaete River, Minas Gerais, Brazil, 1935. 80.30 carats. No further information available.

rose. (1) An abbreviated term for a rose-cut diamond. See rose cut. (2) A color in which diamond occurs: a light purplish red. See pink diamond.

rondelle (ron-dell"). Also spelled roundelle. A drilled disc with a vari­able number of facets around the edge. Diamonds cut in this manner, although rarely encountered, are generally used as spacers between beads.

rondisting. Another term for the gir­dling (rounding up or bruting) opera­tion. See girdling.

Roodepan. A minor alluvial diamond deposit in the Ventersdorp area, Transvaal Province, Republic of South Africa. Annual production from this digging is insignificant.

Roodepoortejie. A minor alluvial di­amond deposit in the Lichtenburg area, Transvaal Province, Republic of South Africa. Current production from this deposit is very low.

Rojtman diamond. A large 107.60-carat yellow cushion-cut diamond purchased by Harry Winston, New York City gem merchant, in 1957. It was recut to 107.46 carats, and mounted in an elaborate clip-pendant combination, and sold in the United States in 1963. The Rojtman diamond was exhibited at the De Beers diamond Pavilion in Johannesburg in 1966 by its owner, Mrs. Marc Rojtman. Prior to the ac­quisition of the Rojtman diamond, by the late Marc Rojtman, nothing is known of its history. Some experts believe that it is similar to the Star of Diamonds, a high-quality South Afri­can stone found in the early days of the diamond fields.

Rockwell Indentation Hardness. A technique for measuring the hard­ness of metals and alloys, in which a cone-shaped diamond is pressed to a standard depth into the metal, the relative resistance to penetration (Rockwell hardness) being deter­mined and automatically indicated by a number (Rockwell number) on a dial. The operation is called the Rockwell Test.

rocking cradle. A portable, hand op­erated, sluice and sieve box used by prospectors in separating alluvial materials. Usually, one or two sieves are mounted on two rocker arms, which are agitated by oscillation in water or air. diamond-bearing mate­rials are placed on the screen; fine material is sieved through, collected and washed. The coarse gravels are collected at the top and discarded.