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TOURMALINE
 Tourmaline
is a varied and versatile gem. It comes in every
color, and as with all colored gems the most expensive
will be the ones with the brightest colors. Because
long tourmaline crystals sometimes show two colors,
these shapes will be set into jewelry. Once again,
the two colors--their respective vividness and
their collective contrast--will determine price.
The most expensive varieties
are the green chrome varieties from Tanzania,
and the amazing bluish Brazilian stones know as
Paraiba tourmalines. Chrome tourmalines rival
emeralds in color, and cost almost as much. Paraiba
tourmalines are even rarer and more expensive
and rank among the most precious of gems, with
colors and prices that rival the finest sapphire
and tanzanite.
Fine green tourmalines can
run close to a thousand dollars a carat, but are
more often closer to about half that price. Because
they often show an excellent green color, they
are a good substitute for more expensive emeralds
or tsavorites. Pink tourmalines usually cost even
less, depending on color saturation--the preferred
colors are bright lemonade pink and a cranberry-red.
Tourmalines that are ruby colored are called rubellite
tourmalines, and they cost more. There's ample
proof that rubellite tourmalines make excellent
ruby substitutes--royal families were fooled for
centuries.
Most tourmalines are heat
treated to improve color. This process is permanent
and stable. Tourmalines are also commonly irradiated
to improve color. Unlike with some other gems,
irradiation is a stable and permanent process
with tourmalines. Since tourmalines are not especially
prone to inclusions, oil treatments or fracture
filling are rare.
Tourmaline rank around
7-7.5 on the Mohs scale of hardness, and can be
set in a variety of ways safety. They are less
prone to chipping than emeralds or other gems
that have more inclusions. Tourmalines can be
safely cleaned with warm water and mild soap,
but mechanical cleaners should be avoided.
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