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Ch. 13: Buying Diamonds

Ch. 13: Buying Diamonds Page of 153 Ch. 14: Synthetic Man Made Diamonds Text size:minusplusRestore normal size  Mail page Print this page
THE BOOK OF DIAMONDS
through a diamond, a constant, correctly shaped spray of oil is delivered and the efficiency of the nozzle is not im­paired by the action of grit or acid in the oil, or by the great heat.
Boring the hole in a diamond for a die or a nozzle is an interesting process. A needle, impregnated with diamond dust, hammers away on the stone for about a week before the hole is bored. This drilling operation costs seven times as much as the diamond itself.
About forty-five per cent of the product of African dia­mond mines consist of bort, an opaque dark colored variety of diamond, called also black diamond. Such crys­tals weighing from one-half to one carat each are used extensively as teeth in stone-saws for sawing marble and stone for building purposes.
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Ch. 13: Buying Diamonds Page of 153 Ch. 14: Synthetic Man Made Diamonds
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