Gemstones Valuation
No Diamonds
Clarity
The clarity of a gemstone expresses something about the amount of inclusions. Gemstones can vary from complete
opacity to lucid clarity and may contain inclusions (crystals, gas or liquid). Sometimes certain inclusions
are highly distinctive and are a reliable indicator of identity (Emerald "jardin"). Sometimes inclusions even
increase the value of a gemstone ("Horsetail" inclusions in Russian Demantoid).
A magnifying glass or microscope (10x magnification or higher) is the most useful tool for identification of
gemstones, of course in addition with a good eye.
Classification
of Clarity
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1
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very extended image shows a clean stone
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A
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very clear, very brilliant
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2
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eye clean - with the bare eye looking clean
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B
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clear and brilliant
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3
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small or a few not disturbing inclusions
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C
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transparent
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4
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small inclusions, light inclusions
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D
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translucent
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5
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many resp. disturbing inclusions
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E
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opaque
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1 - 5 Explanation of Clarity - Inclusions,
Cracks, Cuts, mineralic Inclusions
A - E Explanation of Appearance - Clarity, Color Distribution, and Brilliance
Color
The color quality of a gemstone on a photo is hard to determine. It depends on the illumination when
the photo was taken as well as on the hardware settings of the pc.
Some minerals show different colors (e.g. corundum). Usually gemstones should have an intensive color.
Color variations could cause a certain extra charge, depending on the rarity.
Cut
Gemstones show different cuts. The perfect cut depends on the ability of the cutter. If you buy a gemstone by
just having seen a photo, keep a close eye on the stone's parallel edges. For exact valuation use the help of a noted
gem laboratory.
The modern polyhedron form shows as many facets as possible, which refract and reflect the light as varied as possible.
Until the 16th century only the cabochon cut was in use. This cut is used until today for less valuable gemstones
with too many inclusions or a lower transparency. An exception is the asterism of some minerals, e.g. star sapphires.
In this case the cabochon cut is necessary to show the star, and the transparency usually plays a less important role.
Carat
A gemstone must not weigh 1 carat (ct) or more. But usually 1 ct is a certain psychological barrier re the price.
If you want to buy a valuable gemstone you should not overvalue this "1 ct price border". A 0.9 ct stone is
hardly to distinguish from a 1.1 ct stone, especially if the stone shall be mounted in a ring. Usually the 0.9 ct
stone will be disproportionately cheaper than the 1.1 ct one.
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