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Diamonds are crystalline forms of carbon formed naturally when carbon is exposed to extremely high pressure and heat. The pressure and heat cause the carbon molecules to dramatically rearrange, and when the temperature reduces, if other conditions are right, the carbon atoms in the melting rock bond and build diamond crystals.
The history of diamonds begins in India, where diamonds were first discovered and pulled from the country’s rivers and streams. Historians estimate the people of India were trading diamonds as early as 400 BC, around the same time the Persian empire collapsed.
A perfect diamond by definition would be a transparent diamond, a diamond with out any color that shows no fluorescence to UV light. These diamonds are often referred to as d-flawless, and extremely rare as the conditions for their formation are not often found in nature. In actuality, the vast majority of diamonds form with small impurities or structural defects which are know to disrupt the flow of light in the stone causing some interesting results. These imperfections cause parts of the visible-light spectrum to refract or absorb differently which results in the appearance of color.
The vast majority of the world’s diamonds are found in volcanic pipes know as kimberlites. These kimberlites carry diamonds from deep in the earth’s crust, to the surface of earth where they solidify and host the diamonds within. As these are subterranean, extracting these diamonds requires the mining of this host rock, or diamondiferous ore. This ore is mined from the earth in smaller pieces, and delivered to a process plant for extraction.
Once diamonds have left a processing plant, diamond rich concentrate is delivered to manufacturers for cleaning, sorting, and analysis. At this point any additional material attached to the rough diamonds is removed and a rough diamond goes thorough inspection. Each rough diamond is scanned to determine it’s specific dimensions and if it contains any inclusions or imperfections. This part of the process ensures that a rough diamond is cut in a specific shape and proportion in order to allow it to fetch its highest potential value for the manufacturer.
Once the manufacturer has determined the desired cut, the stone is sent to a gem cutter. Gem cutters have been in existence for over 600 years. The first formal cutters guild was formed in 1375 in Nuremberg, Germany, and was known as the Diamantaire. This guild was directly responsible for the development of the various cuts we see today. When a cutter receives a rough diamond, it resembles a small piece of dull crystal. It is the cutting, faceting and polishing that allows the stones full potential to be realized.
Every diamond is unique, and display a wide variety of properties. Because of this every diamond must be evaluated to some degree to determine it’s value before it exchanges hands, or goes to market. As diamonds became more and more popular, and readily available, there became a great need for a unified grading system. This need lead to the establishment of the Gemological Institute of America (GIA) in 1931 by Robert M. Shipley. The GIA’s mission was and is to protect buyers and sellers of gemstones by creating and maintaining a set of standards used to evaluate gemstone quality. This was no easy task and required much research and innovation.
The evaluation of color can be viewed in two primary categories.
The next c refers to how well the diamond has been cut. This evaluates the way each of the facets of the diamond interact with light. The cut of a diamond is given one of 5 possible grades.
Clarity refers to the quality of the composition of the crystalline form. To determine the clarity of a diamond a gemoligist examines the stone in great detail looking for imperfections in the diamond. These are typically fractures within the stone (inclusions), or on the surface of the diamond (Blemishes). The Clarity scale consists of 11 specific grades.
The final consideration is the actual weight of the diamond. Diamond weight is measured in carats. The carat is a unit of mass, one single carat is equivalent to 200 mg. The definition was adopted at the Fourth General Conference on Weights and Measures in 1907. The term carat comes from the Italian “carato”, which is derived from the Greek kerátion, meaning carob seed, which early traders used as counterweights to balance their scales do determine weight. Diamond weight is measured to the hundred thousandths of a carat (2 decimal places).