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Features: |
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Additional Visual Observation of
Fluorescence.
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Single Button Use.
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High-tech product, made in Belgium (Antwerp)
based on profound market experience in rough diamonds
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Light weight (900 gr)
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Compact(H75xW195xL95mm)
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Colour in diamond : |
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Colour in diamond (also in other precious
stones) is caused by absorption of light. White light consists in a
mixture of rainbow colours. When a number of colours selectively
disappear because of absorption in the diamond, one can notice the
mixture of remaining colours coming back from the diamond.
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When the concentration of nitrogen
impurities of a type Ia stone increases, the blue absorption increases
and the diamond appears to be more yellow. This shows there is a
direct connection between the concentration of impurities and the
colour quotation via the ‘Cape series’. For rough stones it is most of
the time not possible to perform a reliable colour judgement by using
polished 'masterstones'. The "Chromascope Cape" device offers a
solution here.
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The largest part of natural diamond
belongs to type Ia. These stones contain nitrogen impurities, which
mostly appear in groups of 3 nitrogen atoms (N3 aggregate). These
impurities absorb blue light, which results in a yellow colour of the
diamond.
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One of the most important colour scales
for the allocation of the colour judgement of a polished stone is the
'Cape series'. This scale starts from absolute colourlessness
indicated with the letter D. When a stone starts to show a pale yellow
shade, this quotation drops to E, F, G, ... . Polished stones are
compared to 'masterstones' in order to classify them into certain
colour zones.
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The "Chromascope Cape" device measures the
concentration of nitrogen impurities and correlates this with a
judgement within the 'Cape series', in other words, a colour letter is
allocated to the rough stone. Since the larger part of natural
diamonds belongs to type Ia, the colour of most stones can be
determined.
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When using the "Chromascope
Cape", the following restrictions need to be taken into account : |
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For a small part of diamonds, the
yellowness of the stone is determined by other impurities than
nitrogen. These can not be measured by the device.
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The brown tint in a type II rough diamond
will not be measured.
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Strong fluorescent stones can cause
unreliable measurements.
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Often the colour inside a rough stone is
not everywhere the same. The device however measures the average
colour. It is recommended to measure the rough stone in different
areas to get an idea of the colour variation present in the stone.
This colour variation is caused by the fact that the concentration of
nitrogen impurities is not the same in every part of the diamond.
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The "Chromascope Cape" device determines
the colour of the "Cape series" from "D" until "K". When a diamond has
a lower colour than "K" or is "fancy colour", only the measured value
will be given, no colour letter will be granted.
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The Chromascope Cape is a very light (900 gr),
compact (H:75mm W:195mm L:85mm) and friendly to use device to grade
colour and fluorescence in a rough diamond.
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Cape Colours from "D" to "K" can be measured
by one single button use. Even the level of fluorescence will be
indicated. The fluorescence can also be observed visually.
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