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THE
BIRTHSTONE for MAY (Green)
The 8th
ANNIVERSARY STONE
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MOH's scale of hardness
: 7 to 7-1/2
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Specific Gravity : 3.02-3.26
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Refractive Index : 1.616-1.652
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Double Refraction : -0.014 to -0.044
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Paraiba Tourmaline
Paraiba Tourmaline is another of the world's most unusual
Gemstones. At first it was called "Electric" then "NEON." This new
gemstone was discovered in Brazil in 1989. It's brilliant blue and green
are more vivid than any ever seen before. The term "NEON" accurately describes
the tone of color. It is so vivid it will shock you with its beauty. You
can see this stone from across the room! These vivid turquoises, electric
blues, rich twilight blues, and neon greens haven't been seen with any
consistency in any other gemstone variety.
Paraíba-type tourmalines belong to the elbaite species, but contain manganese (Mn)
and copper (Cu) with a Cu content of up to 2.30 wt% CuO, as well as bismuth
(Bi). From the beginning, the trade labeled these
Paraíba
tourmalines (Fritsch et al.,
1990). The name quickly caught on and is now mentioned as a valid trade name in
the CIBJO Rules. Copper was quickly labeled as the principle cause of the rich
color.
Meanwhile, more locations of copper-containing tourmalines were discovered. The
first was in Brazil's Rio Grande Do Norte state, just north of Paraíba state.
This new find was also described as "paraíba tourmaline." In 2001, another
copper-bearing tourmaline locality was discovered, this time in Nigeria (Smith
et al., 2001). The Nigerian gemstones are generally not as vivid as those from
Brazil. Chemically, the Nigerian material can also be easily distinguished by
its lead content, in addition to copper and manganese. But according to the
CIBJO rules, it fits the "Paraíba" definition, and they have been sold under
that name. In 2005, Paraíba type tourmalines from Mozambique entered the market
(Abduriyim & Kitawaki, 2005). Some of this material is much closer in color to
the original Paraíba tourmaline, and often not distinguishable by the naked eye.
The chemical composition is much more complex with varying amounts and large
ranges of Mn, Cu, lead (Pb), and Bi. A large number of these tourmalines do not
contain any Pb, and may easily overlap with properties of the Brazilian
copper-bearing tourmalines. At the international Gemstone Industry Laboratory
Conference (GILC) in Tucson in February 2006, the Conference suggested that the
term "Paraíba Tourmaline" be adapted as a variety name, rather than a geographic
origin. If origin was requested, laboratories could then prepare an origin
report (where possible). Looking at the chemical data, the differences are
sometimes so small and properties overlapping that it may not be possible to
give an origin at all for the occasional stone. Looking at the colors, the best
samples from Nigeria or Mozambique had colors that were as vivid as the ones
from Brazil.
These challenges have kept the laboratories of the international Laboratory
Manual Harmonization Committee (LMHC) busy for several
months before a consensus was finally reached in April. New gemstone
identification reports will call all copper containing elbaite "Paraíba
Tourmaline," regardless of it's origin, and this is consistent with current
trade practice. Production
is very sporadic in all locations, and does not keep up with the strong market demand. These mine shafts are hand-excavated tunnels up to 60 meters deep and the Paraíba
Tourmaline is found only in very thin veins.
So even with the new find, this means the supply
will always be limited and Paraiba always be very rare and expensive. Retail prices
are around $10,000 to $15,000 per carat for fine 2 carat
specimens, and over $20,000 per carat for the fine 3 to 4 carat
specimens, but even that is very little when you realize how rare these
gemstones are. Diamonds are quite common in comparison.
The prices for Paraibas are not the standard by which other Tourmalines can be
measured. The price per carat
reflects the size, clarity, color and the intensity of the particular shade. Neon Paraiba Tourmaline is an attractive, highly desirable Gemstone which
should be purchased when you can. The most desired colors have been the
shades of clear bright greenish Blue or bluish Green; pure Green; or the
medium intense Blue. Naturally variations of tones create exciting
"Neons." Stones are usually transparent with minimal inclusions. This super rare
Gemstone is a definite winner!
TREATMENTS - Fine Gem Quality
Paraiba Tourmaline is
never
treated. However, there are heated gems on the market selling
for a fraction of the cost of fine quality natural Paraiba. It would be prudent
to purchase only gems that have been certified by a qualified independent
gemologist and identified as natural non-enhanced Paraiba. The heated gems
on the market start out as poor color stones that are heated to enhance
the color, but the neon effect is lost during the heating process, so they are
never as good as the natural gems. These lower quality heated gems are always
lower priced, and will never be accepted as true collector specimens.
CARE - Paraiba
Tourmaline is a very good choice for jewelry but it should be
stored in a separate compartment or in a jewelry bag to prevent scratching by
harder Gemstones. It is risky to clean Paraiba
Tourmaline in an ultrasonic or steam cleaner. We
strongly recommend
Ionic
Cleaners and/or warm, soapy water and a soft brush as the best way to clean
Tourmaline jewelry.
LMHC -
is
a group of seven laboratories that work together on harmonization of report
language. The LMHC was founded in 2002, after an annual meeting in Tucson, where
the industry and laboratory representatives meet and discuss current issues. One
such issue was that the various laboratories had different ways of expressing
treatments, and often different standards about quantification as well. Members
of the LMHC laboratories currently involved are: the AGTA Gemological Testing
Center for USA, CISGEM for Italy, GAAJ (Gemmological Association of All Japan)
for Japan, GGL (Gübelin Gem Lab) for Switzerland, GIA for USA, Switzerland and
Thailand, GIT (Gemmological Institute of Thailand) for Thailand, and SSEF Swiss
Gemmological Institute for Switzerland.
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