Rough crystals of diamond (top)
Photo courtesy of Thomas
Hunn Co., Grand Junction, Colorado,USA.
A cut and polished diamond (bottom)
© De Beers |
In the film, after James had found the diamonds, he
looks at them very carefully under a microscope. He
sees that the name Gustav Graves is inscribed on them
in tiny letters. I checked this out and in fact this
can be done. It is a technique called ion beam writing.
Ions are very tiny charged particles. When fired at
a surface of diamond they convert the diamond into graphite
in patterns or writing only 1/40th of the thickness
of a human hair. Graphite is gray in color and so contrasts
against the transparent diamond. Even tiny diamond crystals
can be written on. Some companies inscribe each diamond
coming out of a mine so it can be identified at a later
stage as coming from that particular mine. Wouldn't
you think this would take a lot of time and effort to
write on each one? Well, there are now special machines
that can automatically engrave each crystal in less
than a second. When diamonds come out of the ground
they are rough, they have a crystalline shape but they
are scratched and have rough surfaces. To make them
sparkling and beautiful like the ones we see in rings,
and necklaces, they have to be cut and polished. The
inscribing technique can also be used on cut and polished
diamonds, the name of the jeweler or the company supplying
the diamond to the jeweler can be put on them.
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Diamond inscribed with a jewelers name
Image courtesy of Gemprint
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Besides names, other information can be inscribed on
a diamond. Goods in supermarkets have bar codes - one
swipe and the name of the item and its weight and price
come up on the till. Diamonds can be bar coded too.
Bar codes are, however, quite large, so a new method
has been developed where a pattern of black and white
blocks, called a matrix, is inscribed in to the diamond.
The arrangement of the blocks is related to information
held in a computer database. By swiping the matrix all
the information about that diamonds history can be found
from the database. A big advantage is that the matrix
can be made very tiny.
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A tiny Data Matrix engraved on a diamond can provide full
details of its history
Image courtesy of
Norsam Technologies
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These techniques of writing am matrix words on a diamond
are known as branding. A disadvantage of branding is that
it slightly damages the diamond. During the process, a small
area is converted to graphite. Recently, a new technique has
been developed for identifying individual cut diamonds. Each
diamond has laser light shined on it, which results in a unique
star like scatter pattern of reflected light. No two diamonds
will be exactly the same even if they are cut the same way,
as each crystal will have unique inclusions and faults in
their structures. The light pattern, which is as unique as
a fingerprint or DNA sample, is photographed and kept on a
database. The database holds information about the diamond
that might be important in the future, including its weight,
where is was mined and who sold it to whom.
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