The
price-determinant factors of a pearl are:
1. Shape and Symmetry
2. The Basic Colour
and its Overtone
3. Luster
4. The Thickness of
the Nacreous Cover
5. Condition of the
Pearls Surface
6. Size |
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Shape
and Symmetry
The
shape of a pearl can be devided into three categories:
Round
Symmetrically
(Button, Egg, Drop, Pear)
Baroque
Not
only the symmetry of a pearl´s shape is gradated, but also how concentrically
it was drilled:
1. Perfectly round
and/or exactly concentrically drilled
2. slightly out
of round and/or excentrically drilled
3. out of round
and/or excentrically drilled
4. semi-baroque
and/or excentrically drilled
5. baroque and/or
excentrically drilled
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Colour
and Overtone
The
colour of a pearl is always a combination of the colour of it´s
body and its overtone.
The
overtone can be seen best, when you watch a pearl under diffuse light and
look at a reflection at the strongest curvature. There is always an overtone,
but it can either have the same colour or a completely diiferent:
1. Pink-rose;
white-rose; perfectly black
2. very bright
creme-rose; white-rose with a green overtone
3. creme-rose;
white
4. creme and
white with a green overtone
5. creme to lightly
golden with rose overtone
6. intensive
golden to yellowish colour with a rose or green overtone
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Luster
The
Luster of a pearl is due to the breaking up of light into minute spectra
by diffraction caused by the irregular edges of the overlapping crystal
plates of aragonite, and the interference of light at thin films, given
by the same platelets. The thicker the layer of nacre, that covers the
nucleus, and the more Aragonite-platelets, the better is the luster.
To gradate the luster,
you have to look at the reflection of light on a pearl´s strongest
curvature: The focussing of the reflection:
1. very good (nearly
netallic) luster, sharp focussed reflection
2. very good
brilliance, good outlined reflection
3. lebhafter
Glanz, not vitreos
4. medium sparkle,
slightly unfocussed reflection
5. slightly dull,
looks like porcelain |
Thickness
of nacrous cover
The
durability of a pearl mainly depends on the thickness of the nacrous layer,
that covers the nucleus.
The gradation is
done by looking for the "Blinking Effect" and by lookink into the
drill-hole.
The "Blinking
Effect" is foundet upon the reflection of light at the nucleus. This effect
can be seen best 40 cm away from the source of light, when a chain of pearls
is slowly turned.
1. very thick
2. thick
3. medium
4. thin
5. very thin
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Condition
of Surface
Als
Oberflächenmerkmale einer Perle bezeichnet man punktartige Vertiefungen,
flache Stellen, Auswüchse, dunkle Stellen, Risse...
1. perfectly spotless
2. some minor
marks, but no differences in colour
3. some marks,very
easy to see, but only minor differences in colour
4. may large
marks with completely different colours |
Size
The
maximum size of a pearl always depends on the species of shellfish !
The maximum sizes
of Akoya-pearls are about 10-11 mm, those of South Sea-pearls are 25 mm.
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