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50 % of all diamonds have fluorescence
emitting a light blue or sometimes light green colour
in certain lights. This can only be seen in most cases
under longwave ultra-violet light.
When diamond dealers started to
try to secure a common set of colours so the diamonds
could be explained to each other and traded more freely.
The top diamond was called a Jager. This was the finest
blue white diamond and the name comes from the mine
in South Africa called the Jagerfontein mine.
They then realised that the light
blue was fluorescence, as they appeared as different
hues in different lights. The blue hue appeared as the
result of concentrated ultra-violet rays of light in
natural light. On realising this they changed the order
of quality and the River diamond which had been the
2nd quality became the top stone. This was after diamonds
found in rivers and alluvial deposits, as these stones
were normally very clean and very transparent. The reason
for this is the stones have been eroded out of the pipes
they were formed in over millions of years and have
been washed down stream. The lower grade diamonds have
been eroded away over the years leaving only the best
hardest purest stones intact.
This has now been changed to the
grading system we have in place today. Ranging from
D downwards. ABC has not as yet been used to grade the
colour of the diamond in case a better-coloured diamond
appears in the future.
Discussing this always reminds me
when I was finding a diamond for Jonathon a client and
hopefully more than this. He wanted a large marquise
for his wife as a special present. So 2 days later I
had found 2 stones that were very nice and great value
for the money. The dealers I normally deal with did
not have what we were looking for. I had found a couple
of very good stones from an Antwerp dealer I have a
lot of dealings with Ari a chap I have dealt with on
a few occasions in Antwerp his family have been in diamonds
for generations and have there own cutting firm.
I talked to Jonathon at lunchtime,
after 2 days looking at diamonds your eyes become very
sore. He then asked me to save one of the stones, which
I went back to do after seeing the dealer with the stone.
I happened by accident to come across
a D coloured stone with stunning proportions and no
fluorescence. Just within the price range. The other
stones were larger and most people would have chosen
the larger heavier stone. Most of the time I would have
recommended the larger stones but this stone was the
best without a doubt there was no comparison. It was
the best marquise in this particular large size I have
ever seen. So an hour later and a bit more haggling
the stone was purchased.
The American dealer was also one
of the few dealers who really had the same passion for
the stones as I do which showed in his stock.
Most of the time the fluorescence
in diamonds cannot be seen in most lights. Some types
of fluorescence can effect the stone very badly in certain
lights. Also the fluorescence tells you how to mount
the stone in some cases. I have seen stones that look
stunning in white and natural light. Then when you walk
into a room where one of the lights is slightly yellow
(a dirty fluorescence tubes is the worse) the stone
with certain florescence will take on a petrol colour
and lose a lot of fire.
A badly fluorescence stone would
not be set in a rub over setting as the stone would
loose a lot of its fire and colour. I have seen a very
expensive pink diamond set this way and then the seller
wondered what had happened. I did not like to point
out the problem at this point as he did not know about
the fluorescence properties. I don’t think his
boss who was not hands on would have been too pleased.
Yours Faithfully Jeremy
Fischer.
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