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.
