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Chapter VIII GEM-CUTTING AND POLISHING
MOST
of the gem-stones are won as waterworn and damaged or rounded pebbles,
though some good crystals may also be obtained. The value and beauty of
gem-stones are very much enhanced by the proper cutting of facets,
because the optical properties are then brought out to the best
advantage. In cutting it is always the aim to maintain the symmetry of
the crystal.
The
first attempts at gem-cutting were to smooth off or round off the
stones and polish them by crude methods. Gems were also drilled and
used as drops. The old process of cutting is still extant in the
various types of cabochon cuts, which include the following: Convex
cabochon, lentil cut, high cabochon, hollow or concavo-convex cabochon.
They are illustrated below.
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The above cabochon cuts are suitable for stones that have a sheen as the tiger's eye, a play of colours as in opal,
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