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Turquoise
The
best quality turquoise is uniform in color, deep blue,
and free of ¬matrix. Such stones may sell for tens
of dollars per carat. Just below this ¬in value
is fine quality spiderweb turquoise; value decreases
with ¬increasing amounts of matrix. In all cases
valuation is based on overall appearance and depth of
color, as well as the presence or absence of green or
brown tinge.
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Uniformity
of color implies the absence of offcolor patches or
spots. Dark-blue turquoise is considered the most desirable,
while greenish-blue stones are of lesser quality. Yellowish
green material may sell for a few pennies per carat. |
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Turquoise
is somewhat soft -6 on the Mohs scale-but is company and wears
well. Turquoise is always opaque, and therefore is cut into
beads and cabochons that sometimes take a high polish and
have a glassy appearance. Small chips are extensively used
by Indian worker ¬and silversmiths for inlay purposes,
and Indian jewelry with turquoise set in silver has become
very popular. The variety of rings, bracelet, pendants, and
earrings produced is enormous.
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Turquoise |
| Turquoise
Of
special interest and Popularity are the ornate
necklaces called "squashblossom" that
car weigh several pounds and may cost thousands
of dollars, depending or the quality of turquoise
they contain and the intricacy of the workman
ship. American turquoise, with its deep-blue shades,
is well qualified to, this kind of work, because
light-colored Persian turquoise loses effectiveness..
when set in brightly polished silver. Most Indian
craftsmen prefer to cut baroque, or free-form
cabochons, rather than standard¬-d ovals and
other geometric shapes. Persian turquoise, on
the other hand, is routinely cut to standard shapes
and sizes.
Some turquoise is carved into animal figures and
other decorative apes. Turquoise beads are usually
baroque shapes or tumble-polished nuggets. Occasionally
a gem buyer will find a strand of matched round
Beads, perhaps of spiderweb material. Such a necklace
may sell for several thousand dollars if the quality
of the turquoise is high.
The
porosity of turquoise allows the material to absorb
various additives designed to improve the color.
These additives include oils, Wax, and plastics.
Soaking in a solvent such as carbon tetrachloride
is a good way of detecting such treatment, but
also drastically affects the Appearance of the
turquoise when the additive is dissolved out.
Some¬times an oiled or "waxed" turquoise
gem will "sweat" if heated or aced in
the sun. Stones treated with plastics or sodium
silicate (water ass) are harder to detect. Unfortunately
much of the turquoise sold has been treated in
some way.
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Consumer
Tips-In buying turquoise the consumer might wish to obtain
guarantee that the color will be maintained for a specific
period of me, or that the material has been checked for
treatment and what the treatment was. This is especially
important in the case of expensive jewelry containing turquoise
represented as "natural color." All tur¬quoise
offered for sale should be viewed with the thought of possible
prior treatment.
Turquoise
has been synthetically produced by Pierre Gilson of Paris.
his synthetic is dense, uniform in color, and takes a high
polish. It resembles the very finest Persian turquoise,
but is priced much lower.
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