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Diamond Cleaving
In the process of cutting, rough diamonds are generally cleaved or sawed to render them suitable in size for cutting. If it be cleaved, the rough diamond is fastened with cement to the end of a wooden holder and a tiny groove is scratched with another diamond on the stone at the point where it is to be cleaved. The stone is then held by the clamp in correct position, and then a heavy steel blade is placed on the diamond, and this blade is struck a smart tap on the back and the stone divides along the line previously determined. The operation seems very simple, but is one that requires excellent knowledge of the stones as well as experience.
Diamond Sawing
Sawing has been used some twenty years or more, and enables the cutter to divide the stone along any plane, independent of its structure, while a diamond can be cleaved only along its natural cleavage lines. The diamond saw is about three and one half inches in diameter, and consists of a very thin piece of a special alloy, the edge of which is treated with diamond dust. The work is done very slowly, several hours being required to cut one diamond, so that one workman operates a large number of saws at the same time.
After being cleaved or sawed the stone is again examined by an expert, and a plan for further work on that particular stone is determined on. The most important point in this is the location of the table, which when decided upon is marked with an ink circle.
Diamond Cutting
The next step in the process is that called cutting. This work was done entirely by hand, and was called bruiting, until about twenty-five years ago, when machine cutting came into use. In machine cutting a rough diamond is fixed by cement in a steel holder held in a lathe and is cut by another diamond, which is also fixed into a steel holder attached to a handle some eighteen inches long, this latter diamond being held against the one in the revolving lathe and the cutting done much after the manner of wood turning. The stone is cut very rapidly as compared with the old method of bruiting, the method which had been used from the time of the first cutting of diamonds until the advent of machine cutting. Machine cutting, however, can be used only for round and oval diamonds, and for the round ends of pear or drop shape diamonds. Marquise shape, square or emerald cut, and other fancy shapes must still be cut by hand. |
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Precious Stones Guide Vol 3
>> About the Early Methods of Cleaving, Sawing, and Cutting Diamonds
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