All About Diamonds: Their Origin and Properties

The diamond is generally regarded as the premier gem of the world. Solitary in its chemical composition among precious stones, it is pure carbon, a primary fact that is not as commonly known as it should be and is supposed to be. It seems, indeed, incongruous that such common substances as graphite and lamp-black should be the same, save that they are uncrystallised, as this prince of gems; yet notwithstanding its humble connections, the diamond, in its adamantine lustre, high refraction, reflection, and dispersion of light, and hardness, is alone among minerals. Despite its hardness, the diamond is not indestructible; diamond will cut diamond; it can be burned in the air, being carbon, and will then leave behind carbon dioxide gas and, as ashes, an impurity called carbonado. The facets of a cut diamond can be worn away to some extent by the constant rubbing of fabrics, as is often manifest by contact with wearing apparel. The diamond is also brittle so that it may be easily fractured, especially at the girdle, by striking it a blow against some hard substance, and in a steel mortar with a steel pestle it may be reduced to powder. By what process in Nature's workshop carbon was crystallised into the diamond is unknown, but scientific investigators agree that the process was slow and a prime factor was a titanic pressure.

The specific gravity of the diamond is 3.52; hardness, 10; crystallisation, isometric; cleavage, octahedral and perfect; refraction simple, with an index of 2.439; a high dispersive power; lustre, brilliant adamantine; is combustible though infusible; electric, positively, by friction and a non-conductor of electricity; it is phosphorescent and does not polarise light.

There are three forms of diamonds: crystallised, used as gems; crystalline--imperfect crystallisation,--harder than crystals, termed bort (a word also applied to chips, waste, and stones unfit for cutting); and carbonado, steel gray or black, shapeless, and without cleavage.

To the diamond's surpassing property of dispersing light, or dividing it into coloured rays, is due that fascinating flash of prismatic hues termed its fire. The stone's wondrous brilliancy is due in part to the total reflection of light from its internal faces when the incident ray strikes it at an angle of a little more than twenty-four degrees. Colourless diamonds are richest in the flashing of prismatic hues, while in some coloured specimens it is scarcely apparent; at the same time by-waters, yellow-tinged stones, are sometimes more brilliant in artificial light than are the colourless diamonds.

Diamonds have a wide range of colour; most numerous are the whites, yellows, and browns in a great variety of shades; then come the greens; red stones of strong tints are very rare, as are also blue, which have been found almost exclusively in India; other tints of occasional occurrence are garnet, hyacinth, rose, peach-blossom, lilac, cinnamon, and brown; black, milky, and opalescent diamonds are among the rarities. Diamonds without tint or flaw are rare indeed and even most of the world's famous diamonds have imperfections.

The origin of the diamond's name is the Greek word adamas, meaning unconquerable; from the same root spring our words adamant and adamantine.

The origin of the diamond, according to classical mythology, was its formation by Jupiter, who transformed into stone a man, Diamond of Crete, for refusing to forget Jupiter after he had commanded all men to do so.