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 Rough diamond sorting |
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 Principal crystalline shapes |
| Rough diamond classifications |
| Gem quality diamond |
| Industrial quality diamond |
| Crushing-boart or boart |
| Rough diamonds photos |
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| Principal crystalline shapes |
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  Diamond crystallizes in the cubic system and its crystalline shapes are thus numerous, the principal
ones are:  Octahedron
Dodecahedron
Cube
Rhombododecahedron
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| Rough diamond classifications |
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After diamond was recovered, it will have to be
sorted according to certain categories before being sold:
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Diamonds for cleavage. |
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Diamonds for sawing. |
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Diamonds for cutting. |
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Industrial diamonds. |
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Rough diamond can be sorted according to 3 distinct categories:
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Gem quality. |
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Industrial quality. |
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Crushing-boart or boart. |
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| Only 20 % of the world production of rough
diamonds are intended for the jewellery (gem quality) and 80 % for the industrial uses. There would be
more than 5,000 possible rough diamond classifications. |
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| Gem quality diamond |
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 It is this type of quality which will
be used in the jewellery industry. It must be of good colour and of good clarity, its shape is
not very important because the diamond must be cut. This category of diamond requires a classification of the stones by
subcategories:
Images from http://www.diamondrough.com/ |
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The stones: very beautiful stone of more than 1 carat. |
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The fancy colours stones are those with colour that
does not lies between the bluish white and the yellowish. The colour of fancy
colours diamonds is blue, green, pink, yellow, brown, etc... |
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The closed stones: are monocrystals, beautiful shapes,
good for sawing and polishing. |
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The spotted stones: are monocrystals, beautiful shapes,
these stones have inclusions but it is possible to make them disappear with the cutting. |
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The naats: are deformations of crystallizations, they must be cleaved or bruted. |
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The irregular stones: are octahedral or dodecahedral
(irregular shapes), they are directly cut. |
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The cleavable stones: they must be cleaved. |
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The coated stones: the industry have named coated
stones « speculation stones ». A gangue or a film covers them hiding the interior of the stone. They can remain
opaque or let appear a beautiful stone. |
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The frosted stones: are identical to coated, but the
film is translucent. |
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The milky stones: as its name indicates, this
stone has a milky aspect. |
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The blocks: of a particular shape, their
crystallographic orientation is difficult to see. |
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The plats: in fact generally macles are very often
employed for the rose cut. |
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The sands: they are very small stones (less
than 0.10 carat), mostly used for the size 8/8 |
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The commons goods: they are of a very poor
quality and they are the extreme product of the gem quality. |
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The rejections stones: they are of very bad
quality and therefore must be eliminated. |
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| Industrial quality diamond |
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 As its name indicates, it is the quality
of diamond which is reserved for industry. Industrial diamonds must nevertheless be of a good quality. The yellow color is
preferred because of a greater hardness. One classifies them according to the weight, lower than 3
carats, but also according to their number of point. One uses them for example for the manufacture of dies, the
tools for drilling, etc...
Images from http://www.diamondrough.com/ |
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| Crushing-boart or boart |
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 It is the worst diamond quality which exists, it is generally crushed and will be used as diamond
dust which is used during the diamond polishing.
Images from http://www.diamondrough.com/ |
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| Rough diamonds photos |
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1.94 carat F-SI1 |
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1.99 carat F-SI2 |
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0.23 carat H-VVS1 |
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1.74 carat E-SI2 |
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1.36 carat H-VS2 |
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| Price: £ 8,969 |
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| Price: £ 9,618 |
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| Price: £ 217 |
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| Price: £ 6,924 |
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| Price: £ 5,925 |
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