Abstract
The exceptional hardness of the diamond and its resistance to abrasion are becoming more widely appreciated throughout the industrial world and resulting in its increasing use in the manufacture of drills, drill crowns, crowning wheels, hardness indenters, lathe tools, nozzles, saws, wheel dressers, wire-drawing dies, and many other products.
The industrial diamond as distinct from the gem diamond is, broadly speaking, one that—on account of imperfections such as inclusions, spots, cracks, cuts, inferior crystal form, or dark colour—cannot be economically cut and utilized as a gem stone. The unit of weight for industrial diamonds, like that for the gem stone, is the metric carat; which is equivalent to 0.2 gramme. Approximately 
tons of diamonds a year, an amount corresponding to about 80 per cent by weight of the world's present annual output, is used in industry.
The increasing demand for industrial diamonds was responsible for the reopening of the mine in the Transvaal in which the modern mechanical plant described in this paper was installed.
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