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Diamonds are polished on a polishing wheel covered with diamond dust and oil. The wheel is about eleven inches in diameter and made from a special casting of a secret alloy known only to two men, one in Amsterdam and one 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.
Method of Holding Diamond Polisher
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 the 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 old-fashioned dop of soft metal must still be used. |
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Precious Stones Guide Vol 3
>> About Early Methods of Diamond Polishing
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