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I Break Three Times Into Diamonds 163
When
the stone has been rough-shaped and is ready for faceting and
subsequent polishing, it must be fitted into some contrivance, for it
would be impossible for the cutter to hold it in his bare fingers
against a metal disk revolving at high speed. The device used is a
copper holder into which the stone is securely fixed, and the manner of
fixing it is technically described as "soldering".
Now
the stone is ready to receive its first facet. It is held down against
a porous cast-iron wheel which has previously been edged with a liberal
mixture of oil and fine diamond dust. The wheel turns with a speed of
some 2,500 revolutions per minute. Skeif is the technical name for such a wheel, and the holder containing the stone is known as a dop. The
diamond powder is prepared by pounding in a mortar small, discoloured,
badly flawed or broken crystals of diamond which have no jewel value.
For
the final operation, that of polishing, steel, leather and felt disks
are used, and the diamond powder applied to these removes the last
vestiges of roughness and all scratches or surface blemishes. If any
drilling has to be done, the drill to be used is tipped with a diamond
splinter. The diamond has now finished with the beauty parlour and is
ready to face the critical world.
All
these processes have been perfected only in comparatively recent
times. But yet, as has been said, gem-cutting in its crude form has
been known since antiquity. There are on exhibit in the Museum at
Cairo, stones which, although they have been only crudely cut, bear
witness to the fact that gem-cutting was practised in Egypt in the
early part of the third dynasty, which takes
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