Home arrow Home arrow Progress Diamond proportion of diamonds to blue ground proportions ProportionScope Punch Jones Diam
Progress Diamond proportion of diamonds to blue ground proportions ProportionScope Punch Jones Diam PDF Print E-mail
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Sunday, 23 September 2007

Progress diamond. An 80.66-carat rough diamond found in the Mir pipe. Now in the U.S.S.R. diamond Fund in Moscow.

proper proportions (of a diamond).

See AMERICAN CUT; TOLKOWSKY, MARCEL; PRO­PORTIONS; PROPORTIONS, GOOD.

proportion of Diamonds to blue ground. See richness of maior diamond

DEPOSITS, RELATIVE.

proportions. A term that meant orig­inally the distribution of the mass of a fashioned diamond above and below the girdle. Use by diamond men has broadened its meaning to include the major factors that deter­mine cutting quality; i.e., total depth as a percentage of the girdle diame­ter, table diameter, girdle thickness, facet angles, symmetry, and even de­tails of finish. See proportions, good;

CUTTING; AMERICAN CUT; TOLKOWSKY, MARCEL; FINISH; SYMMETRY.

ProportionScope. A diamond-grading instrument designed and first manufactured by the Gemological Institute of America in 1967. It is an optical comparator for the checking of the proportions of a brilliant. It combines lenses and movable mir­rors to project the silhouette of a dia­mond on a screen. Line diagrams of Tolkowsky proportions on the screen, as well as a "zoom" range, enable

proportions, good. The proportions derived mathematically for the op­timum treatment of light are seldom cut today. Present tastes among jewelers apparently have been con­ditioned somewhat by the weight saving and cost reduction made pos­sible through "spreading," for slightly larger tables and thinner crowns. However, there is general agreement that the angles of the Tolkowsky Theoretical Brilliant Cut are op­timum, so any stone of good propor­tions should have a 403/4° pavilion angle, 34 Vi" crown (bezel), (and a girdle of medium thickness). See

AMERICAN CUT, SPREAD STONE, SWINDLED STONE, PROPORTIONS.

Province of the Cape of Good Hope (also called Cape Province or the Cape). A province in the Republic of South Africa, the north-east and east-central portions of which have been, and are, important diamond-producing areas. The famous mining town of Kimberley is in Cape Prov­ince near the boundary of the Or­ange Free State.

puinwassers. A term used to describe washers of old tailing (waste washers) in the South African dia­mond fields. pulsator jig. See jig.

Punch Jones diamond. One of the largest United States Diamonds, this 34.46-carat greenish-gray crystal was found in 1928 on Rich Creek near Peterstown, West Virginia. It was dis­covered by Grover C. Jones and his son, William R "Punch" Jones, while playing horseshoes but was not posi­tively identified as a diamond until 1943, when it was examined and tested by Professor Roy J. Holden of Virginia Polytechnic Institute. It is now on permanent display in the Smithsonian Institution, Washington, D.C.

 
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