Diamonds with holes bored in them are also fitted into oil nozzles used in the furnaces of our homes and factories, where a constant, correctly shaped spray of oil is needed.
To bore such a hole a needle, impregnated with diamond dust, hammers away on the stone for about week before the hole is bored. And this drilling costs seven times as much as the diamond itself.
Other industrial uses of diamonds are legion. They are used in phonograph needles; for knife-edges in delicate scales, in hardness-testing machines, as dies for extruding the "lead" in pencils. and for turning ivory, hardwood and bakelite into such things as billiard balls, bowling balls, and doorknobs. posits in Michigan. Indiana, Ohio, Wisconsin and Canada, where they occur in the debris left by glaciers ages ago. A few diamonds turned up in California in the sluice-boxes of gold miners, and a few more in the eastern mountains from Virginia to' Georgia. But stich finds are so rare that they can be classed as curiosities" only.
At Pike County, Arkansas, several thousand diamonds have been found in the "blue ground" or peridotite material. which closely resembles the volcanic pipes in which the famous Kimberly deposits of South Africa are located, The world's chief diamond producers are South Africa, Brazil, and Australia.
Impetus has been given to the present upward surge in the diamond industry by the promising laboratory attempts to produce artificial diamonds now being carried On at the General Electric Corporafion in Schenectady, New York.
Text read from the printed page and cleaned; old type leaves the occasional error.