Main Source of Diamonds
in the World

The important diamond fields of India are located in the eastern and southern portions of the peninsula. Many of the famous old diamond fields in this region are now abandoned, but work is still carried on by the natives in the mines in a district lying to the south of Allahabad and Benares. Many of the world’s famous diamonds were found in India, but at present the yield is small.

Diamonds were discovered in Brazil in the first half of the eighteenth century, and have been mined there ever since. At present, however, the production is comparatively small. They are found in the stream gravels in several different districts, the two most important being located in the provinces of Minas Geraes, and Bahia. The city of Diamantina, Minas Geraes, is situated in the center of the most productive field, the diamonds being found chiefly in the gravels of the Rio Jequitinhonha and Rio Doce. Extensive upland deposits of diamond-bearing gravels and clays are also worked.

About 96 per cent of the world’s output of diamonds comes at present from South Africa. The first diamonds were discovered in the gravels of the Val River in 1867. The diamond-bearing gravels covered a considerable area but were not very thick. Later the diamonds were discovered embedded in the rock of several volcanic necks located near the present town of Kimberly in Griqualand- West south of the Vall River, near the boundary of the Orange Free State. The diamonds in this district were first discovered in the soil resulting from the disintegration of the underlying diamond-bearing rock. This soil was colored yellow by iron oxides, and was known as the “yellow ground.” The underlying, undecomposed peridotite rock from which the diamonds are obtained at present is called the “blue ground” The principal mines are the Kimberly Du Toitspan, De Beers and Bultfontein, near Kimberly, the Jagers-fontein in the Orange Free State, and the Premier in the Transvaal. The mines were originally worked as open pits, but, as they have increased in depth, underground methods have been adopted. The blue rock containing the diamonds is brought to the surface, crushed into coarse fragments and spread out on platforms to gradually disintegrate under atmospheric influences. The resulting gravel is washed over and concentrated, the diamonds being finally separated on shaking tables that have been coated with grease, to which the diamond crystals stick, while the rest of the material is washed away. Diamonds have also recently been discovered in alluvial deposits near Luderitz Bay, South West Africa,

Diamonds have been found sparingly in various parts of the United States. Small stones have occasionally been discovered in the stream sands along the eastern slope of the Appalachian Mountains from Virginia south to Georgia. Diamonds have also been reported from the gold sans of northern California and southern Oregon. Sporadic occurrences of diamonds have also been noted in the glacial drift in Wisconsin, Michigan and Ohio. In 1906 the first diamond was found at a new locality situated near Murfreesboro, Pike County, Arkansas. The stones are found here not only in the detrital soil but also embedded in the underlying peridotite rock in a manner quite similar to that of the South African occurrence.