THE BUYING AND USES OF DIAMONDS
the only material used for cutting or engraving the diamond itself.
Diamonds
are now employed not only for faceting precious stones, but also for
cutting and drilling glass and porcelain; for fine engraving such as
the marking of scales; in dentistry for drilling; as twining tools for
electric-light carbons; for finishing accurate turning work such as the
axle of a transit instrument. For these tools the stone is actually
shaped to the best form. It is now electroplated before being set in
its metal mount in order to secure firm fastening. It is also used for
bearings in watches and electric meters.
To
turn machine parts of all kinds is another of the diamond duties. The
Ford Motor Company, for instance, uses many diamonds for this purpose.
Another
important use for diamonds is in drawing wire. Here the metal is drawn
through a round hole drilled in a diamond die. A series of such dies,
with different sized holes, will reduce the wire to the desired
diameter. So hard is the diamond that 300 to 400 tons of copper can be
drawn through such a die before any enlargement of the hole takes
place. That makes a wire, of the diameter used in radio sets, long
enough to go around the world twenty times. Gold, silver, platinum,
iron, and tungsten are also made into wire by this means.
Diamonds
with holes in them are also fitted into oil nozzles to be used in the
furnaces of our homes and factories. This is a rapidly growing use. By
passing the oil
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