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Diamond Color Judging For Jewelry |
In judging the color of diamonds it is necessary to obscure the
prismatic play of colors in order to see the true color. You can do this
by giving the stone a puff of breath and then studying the color while
dim. It must also be remembered that diamonds also have faint color
differences in them. The diamond cutter will often try to cut the diamond
so that it will face up. It is often necessary to view a stone on edge as
well as face up. Often a stone will display better color face up that it
will on edge. These differences affect values that you must be aware of in
order to profit by them.
Some stones have such variation in color according to their positions
that they are called false color stones.
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The stones may seem to be blue
when faced up, yet brown or yellow when seen at another angle. These
stones are often very over priced, if the defect is not detected. Very
few- high priced blue gems are really blue in body color. Most of them
only appear blue due to a bluish fluorescence which becomes more evident
in stronger light. Most of these stones appear inferior to in beauty to
pure white stones when viewed under none fluorescent light. This must be
taken into consideration or more may be paid for a lesser stone.
Another point that must be taken into consideration is that large
masses of stones may appear deeper in tint than similar masses or single
stones. Large parcels often draw color. It is very important to divide
large lights into smaller ones for study and comparison.
A good lens is essential in judging the color of diamonds. You need a
lens that can still see clearly when the object is within an inch or less
of the eye. The true color of a diamond is more apparent when viewed under
a lens. The light from the stone is caught before it has had a chance to
scatter widely. A lens with one inch focal distance is best. Anything more
powerful or less powerful is just not as efficient as a one inch.
Most diamond dealers are still using simple lenses. Better results may
be had from the newer triplets. The triplets consist of three lenses
balsamed together as one, and have six polished curved surfaces so
arranged as to correct all color defects. Pure white light passes the lens
untinted. With the triplets the field of view is clear from edge to edge.
The triplets cost more than the old style, but the triplets are on a whole
new level.
Stones should be judged when they are unset, when the color of the
stone is being determined. At times the color from the mounting can throw
off the appearance of the stone. Unfortunately there is no hard and fast
standard of color to which on can refer doubtful cases. There is a pretty
generally accepted series of names of grades which are supposed to
describe definite degrees of color according their value.
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