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Tanzanite: Prize of a Gem
Safari
The gemstone discoveries in East Africa
in the 1960s transformed the jewelry world: new varieties, new colors, and new
variations on existing species made that decade the most exciting time in the
gemstone industry in our lifetimes.
But no gemstone discovered in East
Africa has had more of an impact on the world gemstone market than tanzanite, a
velvety blue variety of the mineral zoisite that was found for the first time in
1967 and named after the country of its birth by Tiffany & Co in New York,
who introduced the gemstone to the world market in 1969.
Tanzanite is the ultimate prize of a
gem safari. Its rich purples and blues often have a depth comparable to the
finest sapphire. Paler tanzanite has a delicate periwinkle color like the eyes
of Elizabeth Taylor. It is supremely rare, coming from only one place in the
world, the Merelani Hills of Tanzania, in the shadow of Mount Kilimanjaro.
New mining techniques and the
liberalization of the Tanzanian economy has helped to boost production in the
past few years to make tanzanite more available than ever before in the history
of the gemstone.
The source of its mesmerizing color is
that tanzanite is trichroic: that is, it shows different colors when viewed in
different directions. One direction is blue, another purple, and another bronze,
adding subtle depths to the color. When tanzanite is found in the ground, the
bronze color dominates. However, with gentle heating, the cutter can watch the
blue color bloom and deepen in the stone.
Legend has it that the affect of heat
was first discovered when some brown zoisite crystals laying on the ground with
other rocks were caught in a fire set by lightning that swept through the grass
covered Merelani hills northeast of Arusha. The Masai herders who drive cattle
in the area noticed the beautiful blue color and picked the crystals up,
becoming the first tanzanite collectors.
Choosing a Tanzanite
The color of tanzanite is most intense
in sizes above ten carats. Smaller tanzanites are usually paler in color.
Tanzanites which are more blue rather than purple tend to be more expensive
because the crystals tend to form with the blue color axis oriented along the
width of the crystal instead of the length. That means that if the cutter
chooses to maximize the purity of the blue color, the stone cut from the rough
will be smaller and will cost more per carat. The blue color, however, is so
beautiful, that the sacrifice is often worth it.
Tanzanite jewelry is a little more
delicate than other gemstone jewelry and should not be set in a ring that will
be worn during strenuous activity. Never clean tanzanite in an ultrasonic
cleaner or resize or repair a ring set with tanzanite because the stone could
shatter in the heat of a torch. It is available in a variety of shapes and
sometimes in large sizes that are perfect for an important necklace.
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