Congo Diamonds

A few thousand Diamonds were first unearthed in the Belgian Congo in 1910 and, as a result, extensive prospecting followed. Soon there was uncovered a vast Diamond field extending through the Congo and running into Angola, a diamondiferous-bearing area of almost 400 000 square miles. This Congo field is by far the biggest single source of Diamond in the world, accounting for perhaps 60% of world output. The production is almost entirely of industrial quality, very little being suitable for gemstones. This has made the region of immense import­ance politically, and the tensions and dissensions of recent years in this area have had important repercussions. For instance, the possible withdrawal of Congo sources from internationally agreed marketing systems has been a prime instigator in the development of the manufacture of synthetic Diamond grit, as we shall see later. The Angola extension of this field of Diamonds has a good deal more of Gemstone quality in it than the Congo field.

The search for Diamond was taken up in other areas of the African continent. There was and still is an insatiable market for Diamond. In 1919, rich fields were uncovered in Ghana and these are now being worked. Then in 1930 a field was exposed in Sierra Leone. Here in 1945 a beautiful and remark­able gem of 770 carats was discovered. (The writer had the opportunity of examining this briefly before it was cut into GEMS.) It was a cleavage piece and, at a guess, the original might have been 1000 carats or so.

A notable mine was that discovered in Tanganyika by Williamson at Mwadui in 1940. Williamson, a trained geolo­gist, prospected for six years before striking lucky about 90 miles south of Lake Victoria. Here he found a kimberlite type of volcanic pipe. The surface area this covers is 250 acres, i.e. over one-third of a square mile, and this is the largest Diamond pipe in the world. The mine is very rich and produces over 300 000 carats a year. Indeed, since its inception more than half a ton of Diamond has been extracted, and this has required the sorting of 10 000 000 tons of ore. This con­centration of one part in 20 000 000 is a very high grade of ore. Furthermore, most of the Diamond recovered is of fine gem quality. One exceptional find was a pink Diamond found in 1947, of weight 54½ Carat. This was presented by Williamson to Her Majesty Queen Elizabeth as a wedding gift. Cut to a jewel of 23½ carats it was made the centre of a brooch, surrounded by petals made of white Diamonds from the Williamson mine.