|old-miner onza para diamantes CULET, BRILLIANT CUTopen setting|
|Written by Administrator|
|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.
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