According to Emporia State University, the extraction of diamonds has been mechanized and updated over the centuries to make the technique easier and faster. The majority of diamonds are mined on land; there are relatively few mines for marine diamonds which, according to the Mbendi business information website, are usually smaller than those found on land.
The chemical properties of diamonds were unknown for many centuries, with many theories put forward about the unique hardiness and bright appearance of the gems. According to Emporia State University, Sir Isaac Newton put forward a theory in 1704 that diamonds were produced by carbon. Newton’s theory was proven to be correct by the end of the 18th century. Diamonds are found in a variety of colors including blue, yellow, orange, green and black, with the majority of a transparent appearance.
The most commonly used form of extracting diamonds is described by the American Museum of Natural History as open pit or open cast mining. To begin this extraction technique a pit is created; it is dug with steep sides to create a cone narrowing to a point that is connected by roads built into large mines. The large cone is called a kimberlite pipe. Material is removed in large quantities by dump trucks and large loaders. It is then sorted and cleaned at a nearby processing plant.
The American Natural History Museum reports that at ground level and just beneath the surface, tools such as hydraulic shovels and large trucks are used to extract material from the ground. As the pipe is sunk deeper into the ground, dense rock is usually encountered requiring the blasting of material using explosives. Mbendi explains that the value of material removed from a diamond mine is measured by carats per ton of material. The deeper a mine is sunk into the ground, the narrower the area to be mined becomes; precious material becomes less frequent, meaning a reduction in the cost-effectiveness of the mine.
In an attempt to increase the amount of precious material found in a mine, separate shafts are sunk running from the kimberlite pipe through the ground surrounding the mine. According to the American Museum of Natural History, these shafts are sunk both horizontally and vertically, allowing deposits to be mined by hand in areas surrounding the pipe.
To extract diamonds from the vast amount of material removed from the mine, a variety of systems is used to identify diamonds. The American Museum of Natural History describes the initial technique to be the washing of material using a swirling muddy liquid in a washing pan. The washing pan allows heavier minerals such as diamonds to sink to the bottom of the pan, while waste materials float to the surface. A more modern technique is described by the American Museum of Natural History as the passing of material through an X-ray. When a diamond is hit by an X-ray it becomes fluorescent, allowing it to be distinguished and removed from the other material. The final method of extraction used to separate diamonds from waste material is simply by the naked eye.