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Overview of Diamonds and Diamonds ExplorationGeology of Diamonds Diamond is carbon in its most concentrated form. Except for trace impurities like boron and nitrogen, diamond is composed solely of carbon. Diamond, the transparent mineral with the hardest surface known, differs from common graphite simply in its crystal structure. Most diamonds consist of primeval carbon that has crystallised at very high pressures. This suggests that diamonds are created by geologic processes at great depth within the Earth, generally more than 150 km down, in a region beneath the crust known as the mantle. Diamonds rise to the Earth's surface in molten rock, or magma, that originates at great depths, carrying diamonds and other minerals from the Earth's mantle. This magma rises through deep cracks and fissures and erupts in very small but violent volcanoes. Just beneath such volcanoes is a carrot-shaped "pipe" filled with volcanic rock, mantle fragments, and some embedded diamonds. The volcanic rock is called kimberlite after the city of Kimberley, South Africa, where the pipes were first discovered in the 1870s. The complex volcanic magmas that solidify into kimberlite are not the source of diamonds, only the elevators that bring them to the Earth's surface. Kimberlite magma rises through the Earth's crust in networks of cracks or dykes. The carrot-shaped pipes, or diatremes, form near the Earth's surface as a result of an explosive eruption. The base of the pipe, or "root-zone" starts in fissures a few kilometres beneath the surface at the time of eruption. When the kimberlite magma encounters fractures in the Earth's crust at this level, gases are rapidly released from the rising magma - akin to releasing the cork in a bottle of champagne - and this drives the eruption at supersonic speeds; blowing out the fragment-laden kimberlite to form the volcanic pipe. Such eruptions must be incredibly violent. None are known to have occurred during human history. Geologic processes create two basic types of diamond deposits, referred to as primary and secondary sources. Primary sources are the kimberlite pipes. Secondary sources, created by erosion, include such deposits as surface scatterings around a pipe or concentrations in river channels or ocean coasts. Mining of deposits depends upon sufficient concentration and quality of diamonds. Production of Diamonds For 1,000 years, starting in roughly the 4th century BC, India was the only source of diamonds. In 
Most of the diamond deposits first discovered were alluvial - concentrations in streambed or riverbed sand and gravel. They are still actively exploited in many ways, from the most primitive to the highly sophisticated. The goal is relatively simple: to find a location where moving water has deposited diamonds in the bottom of a channel, possibly in a pocket or cleft. Irrespective of whether the mining operation uses shovels or earth-movers, the basic process involves removing the overlying barren ground, digging up the bearing ground, extracting the diamonds from the surrounding materials and, nowadays, restoring the landscape when finished. Mining of a diamond-bearing pipe starts with the excavation of a pit into the pipe. In this open cast mining process, the initially loose and eventually hard ore material is removed with large hydraulic shovels and ore trucks. Hard rock is drilled and blasted with explosives so the broken material can be removed. When deep, rich ore warrants it, the mining goes underground with vertical shafts descending to horizontal passageways that enter the pipe. Once a mining operation yields ore, the diamonds are separated from the other materials and graded for gem or industrial uses. A diamond's beauty, rarity, and price depend on the interplay of all the 4Cs - cut, clarity, carat, and colour. The 4Cs are used throughout the world to classify the rarity of diamonds. Diamonds with the combination of the highest 4C ratings are more rare and, consequently, more expensive. No one C is more important than another in terms of beauty. Uses of Diamonds It is believed that diamonds have been prized as a gemstone as well as for their more industrial uses since at least the 4th century BC. Diamonds first began appearing in European jewellery in the 13th century but remained a rare gem, associated with the aristocracy, until the 1870s, when the first South African discoveries began to reach more public hands. Some 80 per cent. of the diamonds mined annually are used in three primary industrial roles: it is used as a cutting tool, it is embedded in another material and used as a tool or abrasive, and it is turned to powder or paste for grinding and polishing. It is commonly used to fashion stones, ceramics, metals, and concrete, as well as glass lenses, gems, and computer chips. Markets for Diamonds Until the 1870s, diamonds were a scarce resource, found only in riverbeds in India and Brazil, whose elevated price was justified by the fact that only a few pounds of gemstones were produced each year. However, the discovery of the first diamond mine near the Orange River in South Africa resulted in a much increased supply of diamonds on the market. Realising the need to control supply, early investors in the industry, led by Cecil Rhodes, formed De Beers Consolidated Mines partly to achieve their desired level of control. Today, the market is still strongly influenced by De Beers as the largest producer of raw diamonds (approximately 48 per cent. of world production in the year 2005). The diamond market is conventionally divided into three segments:
The jewellery and investment segments together represent some 83 per cent. of the value of rough diamonds produced, a chain that starts in diamond mines and results in a cut gemstone sold to a retail purchaser or an investor. Efforts have been initiated to create a global system of export certification and import verification to ensure that all diamonds that are legitimately imported and exported into diamond-cutting, trading, and consuming nations will be of known and verifiable origin. The diamond trade structure includes both large and small well-organised components as well as many smaller, uncontrolled operations. While De Beers controls a large percentage of the diamond shipments to key trading centres, UN data suggest that more than 100 countries worldwide participate in rough diamond exporting. In the past few years, new sources of rough diamonds from Australia, Russia, Canada and parts of Africa have considerably changed the controlled single-market system in a number of ways. A significant quantity and variety of these "outside" rough diamonds have always been sold on the open market and go directly to a select number of diamond manufacturers in the cutting centres, but strains areshowing as the volume of diamonds distributed other than by De Beers grows. There is a long-term relationship between diamond sales and world economic growth. Real (inflationadjusted) interest rates, currency fluctuations, and wealth effects are also significant. Although the diamond market benefited from the rapid growth of Asian markets over the past 20 years, the market dynamic has recently shifted from Asia to the US. The retail value of worldwide diamond jewellery sales was approximately $70 billion in 2005. Prices rose by 9.5 per cent. in 2005 and it is predicted that the value of rough diamond demand will increase by 6 per cent. per year over the next ten years from US$13.4 billion in 2005 to US$23 billion by the year 2015. The diamond industry is being provided with an opportunity to rebuild confidence and adapt to the
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