Gem Type:NATURAL PEARLS
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Weight (CARATS): 160 CTS
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Origin:VIETNAM
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SIZE (mm): 7 X 8 X 8 MM
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Color: BLACK
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Shape: ROUND
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Clarity:VVS
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Treatments:DYED
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Additional Comments:
PIECES- 1 STRAND
THIS GEM STONE IS NOW IN AUSTRALIA AND WILL BE SHIPPED FROM THERE SO PLEASE BE PATIENT FOR YOUR DELIVERY
ARTIFICIAL BLACK DYEING WITH SILVER SALT: Treatment
with silver nitrate solutions (AgNO3) is applied since the nineteen
thirties to Japanese Akoya cultured pearls. The method was used at the
end of the 19th century in the mother-of-pearl industry and natural
pearls were also dyed this way.
The pearls are immersed for a period of several days or weeks to
several months in diluted silver nitrate solution (the dilution ratio
is 3 to 4 per cent) and are kept in a dark room. After this, they are
exposed to a strong light source (either sun light or artificial light)
or they are treated with hydrogen sulphate. Both methods lead to the
deposition of metallic silver in an extremely fine distribution in the
pearl, causing the dark color. The method enables the production of
lighter or darker hues, depending on the quantity of silver produced.
An immersion period of several months is required in order to produce
truly black colors while shorter periods lead to more brownish or
grayish hues.
This means that the nucleus remains white, while the
outer pearly layer takes on the dark color. The deposition of silver
seems to concentrate in the conchioline layer which is often present
between the nucleus and the pearly layer. The distribution of silver
gets less towards the surface of the pearl. In the case of undrilled
pearls diffusion of silver oxide starts however from the surface while
in the case of drilled pearls the silver solution will more directly
find its way to the border area between nucleus and outer pearly layer.
7 Pearl Value Factors:
* Size: Pearl
size is measured in millimeters. Typically, all other factors being
equal, a larger pearl of a certain type is more expensive than a
smaller one.
* Shape:
There are three main categories to pearl shape: spherical, symmetrical,
and baroque. An example of a symmetrical pearl is an oval, while
baroque pearls are irregular in shape.
* Color:
With cultured pearls, look at body color and, if present, overtone.
Bodycolor is the dominant color of the pearl, while overtone refers to
one or more translucent colors that overlie the body color (like blush
on a woman’s cheek). A third component of some pearls’ color is orient.
When present, it looks like a moving iridescence on or just below a
pearl’s surface.
* Luster:
This is the intensity of light reflected from a pearl’s surface. In
general, more lustrous pearls will have a higher value. GIA uses the
terms excellent, good, and fair to describe luster on cultured pearls.
* Surface Grading:
This factor looks at the blemishes, or surface irregularities, on a
pearl. Typical blemishes include bumps, abrasions, and spots; the
visibility of the irregularities will affect the cost. Very few pearls,
however, are completely free of blemishes.
* Nacre Quality:
Fine nacre quality means that a cultured pearl has a reasonable
thickness of nacre around the nucleus as well as a high luster.
* Matching
: This is the uniformity of appearance in strands and multi-pearl
pieces of jewelry, and is judged by the consistency of all of the above
factors.
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Type 1 Gemstones |
The following gemstones are typically inclusion free, even minor inclusions detract from their value. |
Diamond, Amethyst, Beryls(Aquamarine,Morganite), Citrine, Smoky Quartz, topaz, Chrysoberyl, Kunzite, Tanzanite, green Tourmaline, and Blue Zircon |
IF |
Internally flawless under extreme magnification (Very rare) |
F |
Flawless |
VVS |
Minute inclusions under 10x; invisible to the unaided eye |
VS |
Minor inclusions under 10x; usually invisible to the unaided eye |
SI1 |
Noticeable inclusions under 10x; usually visible to the unaided eye |
SI2 |
Noticeable inclusions under 10x; usually quite visible to the unaided eye |
I1 |
prominent- moderate affect on appearance or durability |
I2 |
prominent - severe affect on appearance or durability |
I3 |
prominent- severe affect on beauty, transparency or durability |
Type 2 Gemstones |
Gemstones that normally have small inclusions that do not detract from value. |
Alexandrite, Andalusite, Iolite, Peridot, Rhodolite, Ruby, Sapphire, Spinel, Tourmaline, Garnet, Amethyst, Red Zircon, Tsavorite; Blue, Orange, Purple, Yellow and Parti-colored Tourmaline |
F |
Flawless |
VVS |
Minor inclusions under 10x; usually invisible to the unaided eye |
VS |
Noticeable inclusions under 10x; often invisible to the unaided eye |
SI1 |
Obvious inclusions under 10x; visible to the unaided eye |
SI2 |
Obvious inclusions under 10x; very apparent to the unaided eye |
I1 |
prominent - moderate affect on appearance or durability |
I2 |
prominent - severe affect on appearance or durability |
I3 |
prominent - severe affect on beauty, transparency or durability |
6 mm = 1/4 inch (Approx)
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