Gem Type:NATURAL PEARLS

Weight (CARATS): 160 CTS

Origin:VIETNAM

SIZE (mm): 7 X 8 X 8 MM

Color: BLACK

Shape: ROUND

Clarity:VVS

Treatments:DYED

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.