in
Antwerp. The wheel is set to revolve horizontally at the rate of about
twenty-two hundred revolutions per minute. The time needed to polish a
diamond, say of about one carat, after it has been shaped up ready for
the wheel, is, depending on its hardness, from two to four days.
The
diamonds to be polished were formerly always imbedded in a composition
of lead and tin while the metal was in an almost fluid state. In this
case the workman sets the stone in position at die proper angle with a
pair of pliers and smoothes the still almost molten metal with his bare
fingers. It seems to the observer that it is a miracle that the man
does not burn his fingers, until it is noticed that they have been
calloused by the hot metal to a condition almost like that of leather.
After each facet has been polished the diamond must be removed and reset before a new facet can be begun. The patent dop, invented
about seventeen years ago, which allows the stone to be set at the
desired angle and held by clamps, is about the only improvement in the
process of polishing for many years. This improvement cannot, however,
be used in the polishing of melees, marquise, square, and other fancy-shaped diamonds in which the
