Diamond Cut: If diamonds
are the hardest material on earth, how can they be cut and
faceted?
Since we see
the results every day in jewelry stores, we know that rough diamonds
can be cut, but only by other diamonds -- usually in the
form of diamond dust.
The rough diamond in
the photo below is an excellent specimen of an octahedral crystal,
the most common of the many shapes of rough diamond. This is
called the habit of diamond crystal.
When such a crystal
is fashioned into a brilliant jewelry gemstone, the diamond cutter
takes the stone through many detailed steps, the most important
of which are:
Cleaving
When a rough
diamond is determined to be suitable, it is carefully studied
for every detail of its structure. It will then be marked and
given a sharp blow with a special hammer to separate the stone
into two carefully planned parts. This is a risky undertaking,
and only used in rare cases since the advances in mechanical
cutting devices allow even the most difficult stones to be cut
with little attention.
Cutting
In most cases,
a diamond will be cut with a saw blade. Since diamonds are the
hardest material known (which means they cannot be scratched
with any other substance), only diamonds can cut diamonds. So
the diamond is securely mounted and held against a thin alloy
blade impregnated with diamond dust and covered with linseed
oil. As the blade turns, it carries small particles of new diamond
dust which sticks to the oil and continues the process until
the entire diamond is split in two. This can take several days
for a diamond over 1 carat or more.
Bruting
After a diamond
is the height and width desired, it is crudely shaped into the
round or other shape by rubbing it against another diamond on
a high-speed lathe specially designed for the purpose. The bruter
takes the rough from an octahedral shape to a more rounded shape
in the case of many round brilliant diamonds.
Faceting
Then the long
and precise process begins to create the many facets that you
have seen on diamonds in stores. Each facet is created by grinding
the diamond on a horizontal blade as it spins with diamond dust
and linseed oil, similar to the cutting blade.
First, the large facet at the top is ground until level and smooth.
Then the major facets are created on the bottom (called the pavilion),
followed by the large facets on top (called the crown). Then
the pavilion facets are refined into more facets, followed by
the crown facets. The final touch is often the tiny flat facet
at the point of the pavilion, called the culet.
The finished round brilliant diamond, for instance, will have
58 facets, including the tiny culet and large table facets.
Each step in this delicate
process is generally carried out by a specialist who spends many
years in apprenticeship to accumulate the great skill required.
Every tiny mistake can risk a gem worth thousands of dollars.
Only experience can safeguard nature's treasures and bring out
the true beauty of a diamond.
Robert Hensley
President
Diamond Helpers
Keywords: diamond cutting,
faceting, rough diamond, facet, diamond facet
