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THE ART OF THE CUTTER
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the
directions of cleavage or, to get technical about it, the position of
the underlying octahedron. The lapidary's aim, after all, is to form
the largest possible stones out of the piece entrusted to him. The
chief use of the cleavage method is to free the rough mass of any
awkward or useless excrescence or to enable the cutters later to
eliminate the flaws without too much wastage of material. While the
octahedron, for example, is one of the common forms in which the
diamond crystallizes, it is seldom regular in shape unless quite small.
Usually the most suitable "face" of the octahedron is selected to serve
as the table facet of the resulting brilliant. The rough mass is
described as of a particular "point," according to the relation of the
table to the underlying regular octahedron. The mass is said to be
four-point if the table is cut parallel to the face of the cube (that
is, across a corner of the octahedron so that the resulting section is
square); three-point, orWass, if the table is parallel to an octahedron
face; two-point, if the table is parallel to a face of the dodecahedron
and therefore to an edge of the octahedron, while equally inclined to
its two faces meeting in that edge.
These
things admittedly may be highly technical to the average lay reader but
they must be mentioned just in case some technical authority on the
subject is lurking behind the pages of this book waiting for "flaws."
What they come down to is this:
Since
the hardness of a diamond varies perceptibly with the "direction" in
the crystal, it is important that the cutter determine the point of the
"mass" before beginning to work on it. So it is more essential to take
his precious time than to make a hasty decision, for it would be
disastrous if the stone should split in the wrong direction or if
flaws should develop. But once the position of the cleav-
(85)
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