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Tanzanite
is found only in Merelani Hills of Tanzania, in the shadow
of Mount Kilimanjaro. A “velvety” blue variety of the
mineral zoisite, tanzanite is a gem of the twentieth
century, introduced to the world market in 1968 by Tiffany &
Co, who named it in honor of the country of its birth.
History and Lore
Almost all
Tanzanite begins its life as brown as the hills where it was
discovered in 1962 : only heat uncovers the beautiful blue
that has made it famous
Legend has
it that the effect of heat was first discovered when some
brown crystals laying in the ground were caught in a fire
set by lightning that swept through the grass covered
Merelani Hills. The Masai herders who drive cattle in the
area noticed the beautiful blue colour and picked the
crystals up. Becoming the first Tanzanite collector.
Tanzanite
is trichoric : that is, it shows different colours when
viewed in different directions. One direction is blue,
another purple, and another bronze, adding subtle depths to
the colour.
Quality, Value and availability
Tanzanite
ranges from a pure rich blue to strong violet. The blue
colours are more valuable.
Since a
Tanzanite crystal has both blue and purple present, with the
different colours visible at different angles, a gem cutter
must carefully orient the cut stone to maximize its colour.
Blue is usually visible on the short axis so that maximizing
it requires a sacrifice of weight, although the colour is so
beautiful it is often worth it.
The colour
of tanzanite is most intense in sizes above five carats.
Smaller sizes are usually paler in colour.
Tanzanite,
although most common in a cushion cut, is available in a
variety of shapes. Larger sizes are also available.
Sources
Tanzanite
is mined only in the Merelani area of northern Tanzania,
near Arusha, which has become a trading center for the gem.
Routine Enhancements
Virtually
all tanzanite on the market is heated to create its blue
colour. Unheated tanzanite is brown. The colour is
permanent.
Care and Cleaning
Tanzanite
jewelry is a little more delicate than other gemstone
jewelry. This gem should not be set in a ring that will be
worn during strenuous activity.
Tanznaite
is sensitive to temperature change. Never clean Tanzanite in
an ultra-sonic cleaner or resize or repair a ring set with
tanzanite without having the stone removed because it could
shatter in the heat of a torch.
Clean
tanzanite with mild dish soap in warm water: use a
toothbrush to scrub behind the stone where dust can collect.
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