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Diamond cutting
Thank you Lodewyk van Berken by Jeffrey Blancq
April 21th, 2006
Diamond cutting begins with the Diamond Pipeline, from the rough to the polished.
The pipeline begins with the rough diamonds at the mines.
From the mines the diamonds are distributed to their sightholders,
or sold via rough dealers to Antwerp, the major rough diamond market,
to the diamond manufacturers at the various cutting centers.
After the rough is polished, it is sold by the manufacturers/exporters,
brokers, or dealers to loose diamond buyers, jewelry manufacturers, jewelry and
watch designers, diamond wholesalers, retail jewelry stores, etc.
The final destination of the polished diamonds and diamond jewelry
being the consumer.
What is diamond cutting? How does the rough stone, which is formed by
prolonged exposure of carbon bearing materials to high pressure and
temperature, become an attractive gem? Whether you have ever asked
this question or not, diamond cutting is both an art and a science.
Up until the fifteenth century diamond cutting had been a primitive
process. This process, cleaving, consisted of placing a chisel at
the rough stone’s weakest point of molecular cohesion and striking it
with a mallet. This created difficulty however because if the precise
point was not located on the diamond’s structure, the adhesion would
be so weak that the diamond could be separated too easily. If the
pressure was applied to the wrong point, or in the wrong direction,
the diamond would shatter. After cleaving the diamond into the basic
shape of the desired jewel the cutter placed it in an egg shaped tin
cup, a dop, and attempted to remove any imperfections in it by
striking it with another diamond. This was done because only other
diamonds were hard enough to cut diamonds. This final step is called
bruting, the first major process through which the diamond is shaped.
It is a process in which force and friction is used to wear away the
diamond into its round brilliant shape. This process was very slow and painstaking
and the cutter was limited by the natural shape of the diamond.
Thank you Lodewyk van Berken
At the end of the fifteenth century a diamond cutter in Antwerp by the name of Lodewyk van Berken invented
the scaif. The scaif was a polishing wheel that was impregnated with a mixture of olive oil and diamond dust.
The scaif revolutionized the art of diamond cutting. The process is this: The rough diamond was
clamped in a dop and held against this whirling disc, while the
diamond dust on it ground away the diamond to the desired angle. It
became possible to polish symmetrically all the facets of the diamond
at angles that reflected the maximum amount of light. The result was
sparkling gems that fascinated the princes and aristocrats of Europe.
In the twentieth century the next major invention to hit the diamond cutting industry was the saw. The saw,
a circular steel blade lubricated continually with oil and diamond powder, allowed the cutter to go against
the grain of the diamond without
shattering it. The diamond saw allowed cutters to salvage jewels from
badly misshapen and deformed diamonds and it required only about
one-tenth carat of diamond dust for every carat of diamond sawed
through. There were some disadvantages with the diamond saw in respect to cleaving, for example it was a
slower process and more expensive, however it became the common method of shaping diamonds in the postwar years.
Diamond cutting in Antwerp went from being an arcane craft to using semi modern machines to polish diamonds.
Diamond cutting was refined again in 1919 when mathematician Marcel Tolkowsky calculated the formula for the
ideal proportions of a cut diamond. Before Tolkowsky discovered the proper mathematical proportions to bring out
the pure brilliance of a diamond, diamond cutters had to rely on their own experience and trial and error to
achieve a beautiful gem. With his formula, a diamond cutter was able to maximize the amount of light a diamond
reflected with relative ease. Tolkowsky’s formula gave the optimum ratio between the angles of facets opposing
one another in a diamond. Following this formula a cutter would achieve the maximum refracted (inner),
light with the least sacrifice of reflected (outer), light. This formula led to the popularization of the
“brilliant cut” diamond, which had fifty-eight facets polished exactly to the tolerances of the ideal proportions.
With the reduction of diamonds to a mathematic formula, it became possible to design semi-automatic machines to
polish diamonds. These machines were known as Pieromatic machines. Within the past ten years the industry has
created new technology such as lasers (for sawing), computer software (for measuring and polishing), and
automated bruting and cutting machines that have brought the industry into the twenty-first century.
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