Progress Diamond proportion of diamonds to blue ground proportions ProportionScope Punch Jones Diam
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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.