From the mineralogical point, a diamond is one of the crystalline varieties of carbon. The graphite rod of a simple pencil has the same composition as the most desired precious stone on earth. The diamond consists of carbon by approximately 99.95% — the remaining 0.05% has various elements that affect the color and purity of the crystal. Its beauty and strength were valued for ages, but only toward the end of the 19th century diamonds began to be studied by chemists, physicists, geologists and mineralogists. Scientists have established the parameters of mineral formation, as well as its «rising» to the earth’s surface. The obtained knowledge allowed an improvement in the methods of discovering new deposits.
All diamonds on Earth formed at a depth of about 250-300 km from one to three billion years ago under the influence of high temperature and pressure. The primary deposits were formed in igneous rock — wherein stones rise to the surface by so-called kimberlite (Africa, Russia) and lamproite (Australia) pipes. During exploitation, open-pit and shaft methods are used. The former is represented in a giant shell crater with a diameter and depth that can reach over one kilometer. They are formed as a result of the blasting operation, followed by exporting the ore to a screening plant, where diamonds are extracted from the broken ground. The development of open-cut mining becomes economically unprofitable at a depth of 500-600 meters, but in rare cases, the funnels can reach one and a half kilometers. Then they move on to an underground (shaft) survey.
Prior to the kimberlite pipes’ discovery, diamonds were found in placer (secondary) accumulations that are located in river valleys (alluvial deposits), as well as at considerable depths of several hundred meters from where the ore is extracted with the dredge’s help. According to some reports, up to 85% of the extracted stones still fall on the placer accumulation and the yield sometimes amounts to several hundred carats per ton of processed rock. It is also worth mentioning that the crystals formed as a result of a large meteorites’ fall — they differ in small sizes and are the subject of exclusively scientific interest.
One hundred and fifty years ago these stones were rare. Prior to the diamond fever in South Africa, the world’s mining of quality stones did not exceed several hundred carats a year. The crystals were found on the strand line of Indian (from 4th century BC) and Brazilian (from the beginning of the 18th century) rivers, and many of them differed in large sizes, enviable cleanliness and sometimes fancy color. According to the legend, diamonds from the Indian Golconda were considered to be the best. Until now, stones from this already-developed source are highly appreciated in the jewelry market. After the discovery of deposits in South Africa at the end of the 19th century, diamonds became much more accessible. Already in the first half of the last century, there were so many of them that the international corporation De Beers began full-scale advertising; thanks to whom the tradition to give a diamond ring for engagement appeared.
Unlike gemstones, whose origin significantly affects their value, talking about a diamond’s birthplace is not taken into account. It is worth noting that since 1998 the UN has imposed a ban on the purchase of diamonds from a number of West African countries, including Angola, Liberia and Sierra Leone — it became known as history as the «Kimberly Process.» The reason; «blood stones» mined in the territory of military operations, where the money from the sale was used to finance insurgent movements, weapons, slave trade and other illegal actions. But it was not so easy to apply the law in practice: «conflict» diamonds were simply exported to neighboring states that did not fall under the sanctions and were implemented there, and also exchanged for weapons and medicine.