The Princeton union. [volume] (Princeton, Minn.) 1876-1976, 1890-11-27
DREs SING DIAMONDS.
How They are Split, Rubbed, Polished, and
Made to Shine ana Glitter.

Made to Shine ana Glitter.
The operation Of cutting diamonds
comprises three phases " splitting,
shaping and polishing. All crystals
possess the property Of easily cracking
in certain directions; in the dia~
mond there are three distinct
directions, without counting sew
eral secondary ones, and cleavers
or splitters call these the threads of
the stone. A good workman always
knows where to find thread, and this
is the way he proceeds: The diamond
to be cleaved is fixed in a convenient
position at the end Of short stick by
means of cement; then to another
baton, and by the same process, is
fastened sharp diamond. Taking in
his right hand the baton bearing the
sharp point, and in his left the one
that holds the diamond to be cleaved,
he rests them at the middle on a box
which is firmly screwed down to his
table, thus forming sort Of lever, and
then he rubs the two, one against the
other, until the sharp stone has made
notch in the other. He uses three
blades, one after the other, in this way,
the first to make groove, the second
to regularize it, and the third to finish
1t or in neat and distinct manner.
Then, holding in his left hand the
baton on which is the stone to be split,
and at the same time a steel knife, the
edge of which is fixed in the ''thread,"
ne hits a good, straight blow on the
back of his knife with a small iron bar.
and the diamond is separated just
where it was intended to be beforehand.
This "cleavage," as it is called, is not
always necessary; still lapidaries have
recourse to it when they wish to take
from the crystal its defective particles,
or to give it convenient shape for after
operations. Cleaved diamonds, or
those still in their, crude shape. that
have no need of undergoing this
operation, pass to the ''brutage," that
is to say, to receive shape or form.
Two crystals are firmly fixed on a
piece OF wood, and then they are rub
bed against each other until they both
assume the required form. This
operation goes on over a box called
an ''egrisoir," because. it receives the
diamond powder, which is termed
''egrisee'' in French, and which is
produced by the reciprocal wearing
away of the two gems. r he diamonds
are now out Of "brutage,'' but they
are still without brilliancy, so it is
necessary to polish them, and this is
how the process is carried on: A
mixture OF lead and tin is prepared;
this is poured into leather mold, and
the stone is placed on top of this
metal cement, which ''coquille,' as it
is called, is then squeezed into kind
OF steel pincers, and placed by the
pollsher on wheel or steel milestone
having rotative movement, but in such
manner that the side of the diamond
alone touches it. The speed of this
wheel is about two thousand two hun
dred turns in a minute, and it is COW
cred with diamond dust. When one
face has been polished the next face
is proceeded with, and so on. The
man who does this work must be very
sklllful and have d good deal of taste
and mathematical precision. He must
know how to find the thread of the
stone, as otherwise it would only ma Ike
hollow furrow on the mill wheel,