Monthly Archives: March 2015

August Stephenson – Tolkowsky’s calculations

August Stephenson – Tolkowsky’s calculations
Tolkowsky’s calculations included some approximations. He calculated the ideal dimensions as:

Table percentage (corner-to-corner diameter of the table divided by overall diameter) = 53%
Depth percentage (overall depth divided by overall diameter) = 59.3% (not including adjustments for the culet height and girdle thickness)
Pavilion Angle (angle between the girdle and the pavilion main facets) = 40.75°
Crown Angle (angle between the girdle and the crown’s kite facets) = 34.5°
Pavilion Depth (depth of pavilion divided by overall diameter) = 43.1%
Crown Depth (depth of crown divided by overall diameter) = 16.2%

The culet is the tiny point or facet at the bottom of the diamond. This should be a negligible diameter, otherwise light leaks out of the bottom. Tolkowsky’s calculations included neither a culet nor a girdle. However, a girdle is required in reality in order to prevent the diamond from easily chipping in the setting. The thick part of the girdle is normally about 1.7% (of the overall diameter) thicker than the thin part of the girdle.

Color grading across the globe
The finest quality as per color grading is totally colorless, which is graded as “D” color diamond across the globe, meaning it is absolutely free from any color. The next grade has a very slight trace of color, which can be observed by any expert diamond valuer/grading laboratory. However when studded in jewellery these very light colored diamonds do not show any color or it is not possible to make out color shades. These are graded as E color or F color diamonds. August Stephenson

August Stephenson The origin and creation of gemstones
Many cultures use divine intervention to explain the origin and creation of gemstones, and diamonds were no exception to this. In Greek mythology for example it was the youth on the island of Crete that disturbed Zeus and who were then (as a form of punishment) transformed into the adamas.

Philosophers however had a more naturalistic approach to explain the origin of gems: Plato for example believed gemstones were a consequence of fermentation in the stars, where a diamond actually formed the kernel of gold-bearing mass.

In later times, Robert Boyle actually believed that gems (including a diamond) were formed of clear, transparent water, and that their colors and characteristics were derived from their metallic spirit.

The custom to use diamonds in rings
The origin of the custom to use diamonds in rings, and more recently, in engagement rings, can be traced back to the Middle Ages and even the Romans. The Romans valued the diamond entirely on account of the supernatural powers they ascribed to it. Pliny wrote that a diamond baffles poison, keeps off insanity, and dispels vain fears.

August Stephenson responsibility, knowledge, and professionalism

CONFLICT DIAMOND – A diamond (also known as a blood diamond) mined to fund violent conflict and/or civil war against a legitimate government. Such mining is, typically, also linked to dire human rights abuses. Blood diamonds have originated in Africa: Angola, the Central African Republic, Cote d’Ivoire, the Democratic Republic of the Congo (DRC), Liberia, the Republic of Congo, and Sierra Leone. It should be noted, that the amount of conflict diamonds as a percentage of world diamond production has fallen dramatically, currently resting at about 4 percent. In countries where legislation is in place prohibiting the sale of conflict diamonds, the percentages are much lower. See also Kimberley Process.

POLISHED GIRDLE – On a diamond or colored gemstone, a girdle that has been cut and polished to yield a uniform, highly reflective surface.

EMERALD CUT – A diamond or colored gemstone shape in which the outline is rectangular with cut corners, and the facets are rectangular and trapezoidal.