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Portuguese West Africa Potaro Riv er potentially flawless Premier Diamond Precious Stones PDF Print E-mail
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Sunday, 23 September 2007

Portuguese West Africa. A name formerly used for Angola, a major diamond-producing country. See an


Potaro River. A source of Diamonds in Guyana, formerly British Guiana.


Potchefstroom. A town in Transvaal Province, Republic of South Africa, and the location of minor alluvial diamond deposits.

Potemkin diamond. See empress euce'nie diamond.

potentially flawless. A term used in the preliminary description of a dia­mond which could possibly be re-polished or recut so as to rate an in­ternally flawless or a flawless grade. Although the weight loss involved is usually small, the demand and price for flawless grades are such that some­times considerable weight is sac­rificed to achieve them. See flawless.

pothole. A circular hole worn into solid rock by the churning action of water on loose stones and sand that abrade the rock. Usually greater in depth than in width. Heavy minerals (diamond, for example) tend to re­main as concentrates, so the potholes, if in an area of diamond-bearing gravels, may contain excep­tionally valuable deposits. See allu­vial DEPOSITS, ABRASION, ALLUVIAL SORTING, GEM GRAVEL, WET DIGGINGS, RIVER DIGGINGS.

Practical Fine Cut Brilliant. This cut originated from practice and serves as the standard cut for judging pro­portions in Germany. With respect to the girdle diameter, a 1939 study showed a crown height of 14.4%, a pavilion depth of 43.2%, a table diameter of 56.0%, and a crown height to pavilion depth ratio of 1: 3.00. The crown angle is 33.2° and the pavilion angle is 40.8°.

Prairie Bird. A minor alluvial dia­mond deposit in the Bloemhof area, Transvaal Province, Republic of South Africa. This digging contrib­utes very little to total South African alluvial production.

Precious Stones Act of 1927. A law that gives the Government of the Re­public of South Africa complete con­trol of all alluvial diamond deposits; i.e., granting of claims and licenses, controlling production, etc.

Premier diamond. This 86.40-carat emerald-cut diamond was purchased by Harry Winston, New York City gem merchant, in 1957. It was set in a pendant-clip combination, with 157 brilliants, and sold through the Geneva office of Harry Winston, Inc., in 1958.

premier diamond. A diamond that appears bluish in daylight and yel­lowish in artificial (incandescent) light; a yellow stone that fluoresces strongly in a blue color. The term is usually applied to fluorescent stones that seem cloudy or "oily" in day­light. See FLUORESCENCE, FLUOROCIIROMA-TIC.

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