TANZANITE
Tanzanite is relatively new on the gemstone market, but has left
its mark. Its blue-lavender color is rather unique and a
wonderful addition to the gemstone palette. Found in Tanzania
(hence the name) in 1967, it has since become a well known and
widely distributed gemstone.
It has better fire than the tourmaline
elbaite
or
peridot
and an adequate hardness. Its only one direction of cleavage is
somewhat of a problem because it is oriented with the
direction
of strongest pleochroism. This would be a problem in most
gemstones because that is the direction the gemcutter would
usually select to maximize the color. However, with tanzanite
the color is usually strong enough anyway.
Pleochroism is very pronounced in tanzanite and is seen as three
different color shades in the same stone. In the viewing a
tanzanite stone, the colors dark blue, green-yellow and
red-purple can be seen, all a result of pleochroism. Lesser
stones may have a brownish color due to the mixing of blue,
purple and green. These stones are usually heat treated to a
deep blue color.
Iolite is a blue-violet gemstone variety of the mineral
cordierite, has strong pleochroism and can be confused with
tanzanite. However, iolite is usually less strongly colored, its
pleochroic colors vary from blue-violet to yellowish gray to
blue and it has less fire. Iolite's unusual color shades makes
it an exotic colored gemstone whose popularity is growing day by
day.
Nearly all tanzanite has been heat treated to generate the
beautiful violet-blue color this stone is known for. When first
mined, most stones are a muted green color. The only known
source of Tanzanite is a five square mile hilltop at Merelani,
ten miles south of the Kilimanjaro International Airport in
Tanzania.
EMERALD
AQUAMARINE
TOURMALINE
GARNET
AMETHYST
