Diamond deposits can be classified as either primary, alluvial or marine. All thee types are present in South Africa. The rocks, in which economic amounts of diamonds are found in South Africa, are known as kimberlites. Only a small portion of kimberlites carries diamonds. The age of diamonds is very important to understand their origin and the subsequent exploration of diamonds. Age determinations are based on inclusions such as garnet and chromite inside the diamond crystal as the inclusion and the diamond crystallise simultaneously. Research showed that diamonds are not genetically related to the kimberlites; diamonds are much older than the rocks (kimberlite) that brought them to the surface.

Erosion of areas containing kimberlite pipes results in the redistribution of diamonds in fluvial (rivers and streams) as well as marine systems. The average value (per carat) for secondary- source or alluvial diamonds increases with transportation distance due to the destruction of fractured (flawed) stones by transportation interactions. Gem-quality diamonds in marine deposits may be as high as 95 %. Diamonds may be transported during semi-arid conditions and “trapped” in sediments due to the changes in sediment erosion and deposition periods of a river, sea-level changes as well as pothole activities. Again, exploration of soil and stream samples for heavy minerals or “indicator minerals” usually gives an indication if the kimberlite source may contain any diamonds.

Diamonds which are not suitable for jewellery are defined as industrial diamonds. They may be twinned, highly included, semitransparent or brown/black. These diamonds are applied in diamond-drilling bits, cutting blades or polishing powders.

Diamonds are synthetically grown, although not commercially manufactured in South Africa. The processes of producing gemquality diamonds are not new, but are very time consuming and expensive. Over a period of time, however, more and more synthetic diamonds will be seen in the trade. In fact, gem-quality synthetic diamonds of cuttable size are being reported and even sold at a number of jewellery shows (Johnson and Koivula, 1996). Many natural, synthetic and artificial products have been used to imitate diamonds.

South Africa’s diamond industry is regulated through the South African Diamond Board by means of the Diamonds Act, 1986 (No. 56 of 1986). The possession of rough diamonds is restricted to producers, dealers and cutters. Rough diamonds mined locally are offered firstly to the local industry (except De Beers), before duty-free exportation is allowed. Illicit diamond buying (IDB) legislation is enforced by the Gold and Diamond branch of the South African Police. Rough diamond imports, which are duty-free, are subject to regulations imposed on local production. No regulations regarding the possession of polished diamonds are enforced in South Africa.