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How Are Diamonds Mined?

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Of all the diamonds mined in the world each year, less than half are gem quality, the rest fall into two other main categories known as near-gem quality and industrial quality diamonds.

Gem quality diamonds display a high standard of excellence in quality and are used in jewelry. The clarity of these diamonds range from flawless to visible inclusions.

Near-gem quality diamonds represent those stones of a quality between gems and industrial, that can be used as either, depending on the individual stone. These stones have clarity grades ranging from visible inclusions to industrial.

Industrial quality diamonds are of low quality or badly included stones and are suitable only for industrial use, such as being used in dentist’s drills and earthmoving equipment.

Over 4,000 years ago the first diamonds were mined in India. Modern mining as we know it today began in South Africa in the late 19th century. Today, the top seven diamond-producing countries are Botswana, Russia, South Africa, Angola, Namibia, Australia and Zaire. They account for 80 percent of the world’s rough diamond supply.

Diamonds are recovered by way of pipe or alluvial mining.

Pipe mining refers to the extraction of diamonds from volcanic pipes. An average of 250 tons of ore must be mined in order to produce a one-carat gem quality polished diamond. In most countries, a diamond pipe mind is composed of kimberlite, or blue ground. Initially kimberlite is dug from the surface of the pipes in rough opencast mining. Once the surface deposits have been exhausted, shafts are sunk into the ground at the edge of the pipes, and tunnels are driven into the deeper parts of the pipes. After the diamond-bearing rock is brought to the surface, it is then transported to a screening plant where the diamonds are separated from the host rock.

Alluvial mining involves the extraction of diamonds from riverbeds or ocean beaches. Millions of years ago, at the time the diamond pipes were formed, some diamonds were weathered out of the pipes and carried great distances along river and even into oceans.

In order to extract these diamonds from beaches, a wall is built to hold back the surf. Up to 25 feet of sand is bulldozed aside to reach the diamond-bearing level. Once it is reached, the diamond-bearing earth is removed and transported to screening plants.

Next Page: How Is A Diamond Cut And Polished?

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