The sun. [volume] (New York [N.Y.]) 1833-1916, 1905-09-03
HOW DIAMONDS ARR CUT.
RIOH INDUSTRY OF ANTWERP
AND AMSTERDAM.


AND AMSTERDAM.
Art That IL Kept secrot-The Three
Distinct Processes-- Cleaning, Brutsgc
and Polishing Of Stone Dc.
ponds On Regular Cutting u Facets.
One Of the richest and most exclusive
trades, that Of diamond outing, Is now con-
fined, 30 far as Europe Is concerned--which
means nearly all the world--to the two towns
Of Amsterdam and Antwerp. and, according
to report recently furnished to tho Foreign
Onioe, the diamond trade Of Antwerp now
equals, II 1t does not surpass, that Of It's
great rival. says the London Dolly Grdphic.
At present the bulk Of the diamond supply
comes from British possessions, or mines
owned by British subjects; and the dia-
monds are sent to London to be sorted and
put up for sale, and. though they 60 abroad
to be cut. they are often returned to be sold.
The difficulty In the way Of developing
q British diamond cutting industry Is that
OF teaching the British workman an art
which the present diamond cutters keep
very secret. Tho Antwerp factories, 1t may
be added, are principally conducted by
Jews, a. arc those Of Amsterdam; and sys-
tenn Of apprenticeship Is In force.
Diamond cutting Is divided into three
separate and distinct processes. which may
be CHASED under tho following heads: First.
oleaving; secondly, the giving Of q rough
formation to the diamond called "brutageD,
and, thirdly, cutting and polishing. The
process Of cleaving Is the act Of dividing
the layers or scales which form the crystal.
This operation can only be performed in
one manner, which it is impossible to vary
ON account Of the fiaky formation OF the
diamond. The stones have to be divided
In accordance with the running grain OF the
carbon Of which they are composed. .Brut-
age Is performed by mechanically rubbing
formation Is achieved. Polishing Is the
final forming of the stone, with it's many cut
surfaces, 80 as to give it sparkle and scintil-
lating beauty.
A diamond is cleft as follows: The rough
stone Is placed in q small metal receptacle.
with the side Of the diamond which it is
desired to cut facing downward. Over
this receptacle is fixed shaped mold, which
Is securely attached to it. Into the top
OF this mold Is then poured liquid alumni
mum, which runs into the shape Of the
holds the diamond in the required position.
The mold is then removed and the stone
remains fixed in the aluminium ready to
be applied to the cutting tool.
The machine used the invention OF a
the cleaving is a small circular saw Of about
four to five inches in diameter which ro-
tates at a high rate Of speed and is driven
In the ordinary way by leather belt from
the running machinery. The saw itself
is made Of fairly soft copper with prepared
operation Of cleaving is taking place that
the saw should run perfectly smoothly
and not deviate from it's true course.
In order to prepare the cutting edge
OF the circular saw it is necessary for 1t to go
through a special process by which dia-
its edge. 1t will therefore be seen that
in the actual cutting the principle is that
of diamond cut diamond The opera
ton of cleaving diamond frequently takes
as much as two weeks continual work to
perform.
The diamonds are frequently out into
several layers hardly thicker than stout
sheet OF paper. For the rough formations
or -brutage," before the final cutting, a
machine was invented some twenty years
tories, since it not only greatly economies
hand labor, but also saves the diamond
dust required for polishing. Two dia-
monds OF similar size and hardness are
taken, and each ia fitted into a metal cap
with melted cement.
"a
apparently lathe) and the other attached
to handle to be used as the tool Is used
against wood in lathe. The stone which
rotates In the machine receives regular
rounded surface. and when it Ia in its Ie-
auired shape the other stone is fitted into
The diamond dust, which is produced by the
rubbing Of the stones together, falls into a
copper box called an egrisoir, or diamond
dust box and is carefully preserved for the
third operation.
For the cutting and polishing process
the stone. which has been roughly shaped
by the second operation, is placed in posi-
ton at the required angle In copper holder.
into which it is firmly fixed by means Of
q. forked clamp. which is pressed against
key. Great skill is required on the part of
the workmen in fixing the diamond into the
holder as will be understood when it is
stated that many stones Of one-eighth
Of an inch and less in diameter, weighing
between one and two grains, have as many
AZ fifty to one hundred facets, or separate cut
faces. each at different angle.
Continual practise, however, facilitates
this operation, and a skilled workman can
Immediately place the stone in the holder
Of another facet. When the stone is ready
in the holder 1t is placed ngair st q revolving
disk OF soft steel rotating in n horizontal
position at a speed Of some 5000 revolutions
to the minute and is left there until the re-
uuired facet is cut and pol shed. The sur
face Of this disk Ia prepared with a mixture
of diamond dust and purified olive oil,
which ia rubbed into the steel.
All diamonds are cut In a series Of stars,
one being formed over the other. On look
Ing through the fat surface OF table of a
properly cut brilliant the colette, or lowest
point should appear to be directly in the
center OF the table. On the regular cutting
Of these facets depends the whole beauty
Of diamond, and in their formation lie
the secret and difficulty Of the diamond
trade.