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Tourmaline
Tourmaline,
a gem not widely known to gem buyers, displays the most
dazzling surpassing variety of colors of al I known
gemstones. Some crystals may display two or three color
bands along their length, or show complex concentric
zoning in cross section. Some of the most delicate,
subtle and exquisite colors in the mineral kingdom belong
to the w group.
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Tourmaline
is actually a general group term that applies to several
mineral with similar atomic structures and chemical
compositions. Confusion sometimes arises because there
are mineral species names (elbaite, schorl, and dravite)
and names for color varieties: rubellite(pink and red),
indicolite (blue), achroite (colorless), siberite (reddish¬
violet) and dravite (brown).Tourmaline has no cleavage,
and therefore doesn't tend to break or chip easily.
Its hardness is 7-71/2, on the Mohs scale. |
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The
color range is vas. In fact. the name tourmaline comes from
the ancient Singhalese word “turamali," meaning "mixed
precious stones." The implication is that Ceylonese gem
dealers could not identify various gemstones, many were undoubtedly
tourmalines.The most valuable tourmalines are red, with a
tinge of purl) violet.
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Tourmaline |
| Tourmaline
The
finest of these come from Maine, California, and
Brazil gradation in hue among the reddish tourmalines
is almost infinite involving mixtures of red,
brown, violet, pink, and orange. African, stones
tend to be pink with a tinge of brown, while gems
from Maine ,¬Brazil are rich violet-red..
California tourmalines are a distinct "shocking"
pastel pink.Green tourmalines are modified by
shades of blue, yellow, a brown. Crystals may
be so dark in color as to be virtually black.
The finest green tourmalines resemble top quality
emeralds, but this colt extremely rare and highly
desired. By far the majority of green to, tourmalines
are mined in Brazil.
A
variety rich in chromium may sell for more than
$100 per carat. The green hues blend imperceptibly
in blue-green, but pure-blue tourmaline is quite
rare. Lilac-colored stone are occasionally found.
Large blue gems may command high prices. ¬Colorless,
yellow, and orange tourmalines are quite rare
and seldom seen in gem form.Color-zoned crystals
are sometimes cut for jewelry use.
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Of
great, popularity are the concentrically banded crystal
sections that are almost always pink in the center and green
on the outside. These have been fancifully named watermelon
tourmaline," and polished crystal slices are worn as
earrings and pendants. Crystals that change color along
their length are called "bicolor" or "multicolored"
tourmalines. Sometimes a tourmaline crystal contains enough
fibrous or tube-like inclusions to display a chatoyant sheen.
When
cut into cabochons such material yields interesting "cat's-eye
tourmalines." These are found in various colors, most
commonly green and pink. Another interesting tourmaline
variety shows a color change resembling that of alexandrite:
yellowish-green in daylight and reddish-orange in artificial
light.
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