line at a cutting off the upper point of the diamond. When this is accomplished, the flat top surface is called the " table." The line at c, which is the largest girth of the diamond, is called its " girdle." The space b, between the girdle and its " table," is called the " bezel." The line at e cuts
off the sharp lower point, and its flat surface is the " culet." The
space between the culet and the girdle is called the " pavilion."
Cleaving Diamonds
There
are three distinct processes in the treatment of diamonds by the
lapidary — cleaving, cutting, and polishing. To split the diamond
successfully demands a thorough knowledge of its individual character
as well as of its generic crystallization and lines of cleavage. The
skilled lapidary takes in hand a large rough diamond. If it is an
Indian or Brazilian stone, it is coated or partly coated with a hard
dull crust. Its corners are perhaps abraded. It may have defects or
cracks in its surface, unequal coloring, or black deposits in its
interior. He must needs remove the crust, correct the distortion of
the crystal, remove or conceal its defects, and decide what is the
largest perfect gem which can be cut from the rough stone. He must be
able to see the priceless jewel through its shrouding veil, and
determine on which surfaces of the stone its prominent corners must
rest. Having decided what shape will best befit the stone, he must know
whether the rejected portions can be split off safely or whether they
must be ground off. Grinding away the rejected portions is probably the
safest procedure, but it is the slowest and most expensive. The
quickest method is to split off the surplus material. The process will
be easy if the proposed fracture is in the direct line of cleavage in
that particular stone. If not, his attempt at splitting may ruin a gem
of countless price. Shall he make the attempt ? He must be both an
expert and a man of nerve. If he be so, a single feat of successful
polishing may bring him fortune and the reputation of a master, while a
single disastrous venture may quite undo him.
