Diamond (gemstone)

Diamonds are such a highly traded commodity that multiple organizations have been created for grading and certifying them based on the "four Cs", which are color, cut, clarity, and carat.

Through an advertising campaign in the late 1940s and continuing into the mid-20th century, De Beers made diamonds into a key part of the betrothal process and a coveted symbol of status.

[11] Another Indian description written in the beginning of the 3rd century describes strength, regularity, brilliance, ability to scratch metals, and good refractive properties as the desirable qualities of a diamond.

In his work Naturalis Historia, the Roman writer Pliny the Elder referred to the adamas (invulnerable stone) that occurred alongside gold and was used for ornament and engraving.

In 1869, an even larger 83.50-carat (16.700 g; 0.5891 oz) diamond was found on the slopes of Colesberg Kopje on the farm Vooruitzigt belonging to the De Beers brothers.

[17] Following agreement by the British government on compensation to the Orange Free State for its competing land claims, Griqualand West was annexed to the Cape Colony in 1877.

[18] From 1871 to 1914, 50,000 miners dug the Big Hole with picks and shovels, yielding 2,722 kg (6,001 lb) of diamonds,[19] and by 1873 Kimberley was the second largest town in South Africa, having an approximate population of 40,000.

In 1888, the two companies merged to form De Beers Consolidated Mines, which proceeded to establish a monopoly over the world's diamond market.

[25] Annual global rough diamond production was estimated to be about 135 million carats (27.0 tonnes; 30 short tons) for 2014,[26][3] of which 92% was cut and polished in India, mostly in the city of Surat.

There are two major non-profit gemological associations which grade and provide reports, (informally referred to by the term certificate or cert, which is a misnomer for many grading reports) on diamonds; while carat weight and cut angles are mathematically defined, the clarity and color are judged by the trained human eye and are therefore open to slight variance in interpretation.

The Gemological Institute of America (GIA) and other organizations have developed systems to grade clarity, which are based on those inclusions which are visible to a trained professional when a diamond is viewed under 10× magnification.

The most common impurity, nitrogen, replaces a small proportion of carbon atoms in a diamond's structure and causes a yellowish to brownish tint.

While even a pale pink or blue hue may increase the value of a diamond, more intense coloration is usually considered more desirable and commands the highest prices.

A variety of impurities and structural imperfections cause different colors in diamonds, including yellow, pink, blue, red, green, brown, and other hues.

There are mathematical guidelines for the angles and length ratios at which the diamond is supposed to be cut in order to reflect the maximum amount of light.

The techniques for cutting diamonds have been developed over hundreds of years, with perhaps the greatest achievements made in 1919 by mathematician and gem enthusiast Marcel Tolkowsky.

Generally speaking, these "fancy cuts" are not held to the same strict standards as Tolkowsky-derived round brilliants and there are less specific mathematical guidelines of angles which determine a well-cut stone.

These newly developed cuts are viewed by many as more of an attempt at brand differentiation by diamond sellers, than actual improvements to the state of the art.

A number of factors, including proportion, polish, symmetry, and the relative angles of various facets, are determined by the quality of the cut and can affect the performance of a diamond.

A well-executed round brilliant cut should reflect light upwards and make the diamond appear white when viewed from the top.

An inferior cut will produce a stone that appears dark at the center and in extreme cases the setting may be seen through the top of the diamond as shadows.

The GIA has developed a set of criteria for grading the cut of round brilliant stones that is now the standard in the diamond industry and is called Facetware.

These stones were actively sought by merchants thanks to their appealing ‘ice’ effect and consumers paid higher prices for diamonds with fluorescence.

Ironically, in 1997, a seminal study by the Gemological Institute of America (GIA) concluded that, "in general, the strength of fluorescence had no widely perceptible effect on the color appearance of diamonds viewed table-down (as is typical in laboratory and trade grading).

Causes for the continuing decline were suggested as lower demand in China, the general global economy, and fewer marriages, but improvement in speed of laboratory growing of diamonds from weeks (and billions of years for natural stones) to hours was thought to be the biggest change.

[54] 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.

[55] In later times, Robert Boyle believed that gems, including diamonds, were formed of clear, transparent water, and that their colors and characteristics were derived from their metallic spirit.

[55] The medieval Italians copied these beliefs and added some to it: they called it the "Pietra della Reconciliazione" (stone of reconciliation) because it maintained concord between husband and wife.

[59] Other early examples of betrothal jewels incorporating diamonds include the Bridal Crown of Blanche (c. 1370–1380)[59] and the Heftlein brooch of Vienna (c. 1430–1440),[59] a pictorial piece depicting a wedding couple.

In the early 20th century, a chairman of De Beers said that the diamond trade would prosper "so long as men are foolish and women are vain.