Cutting and polishing diamonds

India has always been regarded as the natural and ancient home of the
diamonds. Up to 1728 the whole world's supply of diamonds was found in
the deccan plateu in the valleys and on the beds of streams to a depth
of twelve to sixteen feet of earth. Placed there by the gods as a gem
endowed with magical qualities, Indians revered the diamond as far
back as 1500 BC, the age of the Vedas.

During those ancient times, diamonds were not cut. The rough stones
were mounted as such in jewellery, in helmets and on swords. This is
why Indians who wrote on gems, such as Buddhabhatta, Thakkura Pheru
describe the shape, and nature of rough diamonds in great detail. For
example, Thakkura Pheru wrote in 1315 AD: "the best rough diamond has
symmetric facets, free of impurities, sparkling, flawless and ligh in
weight."

Being the hardest known mineral in nature, only diamonds can cut or
abrade other diamonds. Artisan used this property to best advantage;
they rubbed one diamond against another for months to get the shape
they wanted. They were expert in the art of grinding and polishing
diamond crystals and kept gemstone shaping a family secret, not to be
revealed to the outside world. It is likely that their techniques
dated back thousands of years, but there is hardly any mention of this
in Indian literature. Ancient texts state that while the diamonds was
extremely hard and indestructible, it could easily be split by a light
blow along certain directions and that the earliest diamond workers
employed such techniques to remove heavy flows and cracks and to
smooth the faces of crystals. Kautilya in this Artbhashastra wrote of
the ability of diamond to scratch hard metals and other gemstones. It
is possible that Indian workers tried to cut and polish diamonds with
other diamonds as early as the first century BC. In Europe too, as
early as 77 AD, engravers embedded diamond fragments in iron to make
cutting tools. According to Pliny, these tools could in turn cut
diamonds. During his travels in India in the eighteenth century
Tavernier who wrote extensively on the gemstone industry in the
country, found artisan in India were using iron wheels with diamond
grit to remove flaws in diamond crystals. At the time of his visit,
most Indians were merely polishing rough stones that had regular
crystallized shapes. Faults like inclusions and grains were removed by
grinding, but deep faults were sought to be hidden by a great number
of small facets. Some European workers who had practiced diamond
cutting in Europe but had settled in India were given the larger and
more expensive stones for cutting. They were better at this work
perhaps because they had already attained a higher level of perfection
in their work. It has been recorded that as early as 1375 AD, diamond
cutters in Germany were active and had even formed a guild in
Nurenberg.