The diamond-cutting processes involve five stages, consisting of inspection, cleaving, sawing, cutting, and polishing.
(1) Inspection
First
process consists of the examination of the rough stones regarding
crystal form, shape, inclusions, cleavage cracks, flaws, etc., which
have to be properly located. Then ideas as to the style of cutting,
eliminating imperfections, etc., are arrived at. If the stone required
sawing or clearing, the directions in which they have to be done are
marked in Indian ink.
(2) Cleaving
Large
stones are subdivided into smaller ones for commercial purposes.
Inclusions, flaws, etc., are removed, and rough stones are brought to
rough forms with the aid of the octahedral cleavage. To cleave a stone,
it is mounted on the end of a specially designed stick, by the aid of a
suitable hard cement. Next, a groove is made in the direction of the
cleavage, as previously determined. If the octahedral faces are well
developed, the octahedral cleavage could easily be recognized or the
lines of growth or grain have to be determined.
The
groove is cut by a diamond fragment with a sharp edge mounted on a
stick, so. that it could be easily manipulated. The stick, with the
diamond to be cleaved, is then placed in a support with the knife-edge
of a steel plate or cleaving iron, held with one hand in the groove or
notch. The steel plate is given a sharp blow with a small hammer. The
stone breaks or cleaves into two parts parallel to the face of an
octahedron.
Although
it may appear a simple process, cleaving demands most careful work or
the stone may be easily damaged. The cleavage surfaces should be as
smooth as possible, and no particle of diamond should be lost.
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