By Richard
W. Hughes
Introduction/Name
Tsavorite
is the name given to the rich green variety of grossular garnet. The
gem was first discovered in Tanzania in 1967 by Campbell Bridges. In
1970, Bridges also discovered gem tsavorite in Kenya’s Taita/Taveta
district. The name “tsavorite” was coined in 1974 by Campbell
Bridges and Tiffany’s Henry Platt and is derived from Kenya’s
Tsavo National Park, which lies adjacent to rich deposits of the gem.
Color
While
the color of tsavorite never equals that of the finest
emerald, an emerald-green is the ideal. The color
should be as intense as possible, without being overly
dark
or yellowish green. The color of tsavorite is believed
to be due to vanadium, at times with a trace of chromium.
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This
suite of tsavorites shows the typical range of colors possible.
The ideal would be the center stone, which is not too light or
dark. Photo: Wimon Manorotkul; Gem: Pala International |
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Lighting
Tsavorite
garnet generally
looks best under
daylight. Incandescent
light makes it
appear slightly
more yellowish
green.
Clarity
In
terms of clarity,
tsavorite is
relatively
clean. Thus when
buying one
should
expect eye-clean
or near-eye-clean
stones.
Cut
In
the market,
tsavorites
are found
in a variety of
shapes
and cutting
styles. Ovals
and cushions
are the
most common,
but rounds
are
also
seen, as
are
other shapes,
such as emerald
cuts, trillions,
etc. Cabochon-cut
tsavorites
are not
often seen.
Prices
Tsavorite
is among
the most
expensive
of all
garnets,
with
prices
similar to those
fetched
by
fine demantoid
(the
other green
garnet).
But like
all gem
materials,
low-quality
(i.e.,
non-gem quality)
pieces
may
be available
for
a few dollars
per carat.
Such stones
are generally
not
clean enough
to
facet.
Prices for tsavorite
vary greatly
according
to size
and
quality.
At the
top retail end,
they may
reach as
much as
US$8,000
per carat.
Stone
Sizes
Tsavorite
is rare
in faceted
stones
above
7–8
cts.
Fine
tsavorites
above
20 carats
can be
considered
world-class
pieces.
Most
stones
tend
to be
less
than
3 cts.
Sources
The
original
locality
for
tsavorite was Kenya’s Tsavo
National
Park, but today important deposits
of
gem tsavorite have also been found
in
Tanzania’s
Lindi Province.
Enhancements
Tsavorite is one of the few colored gems that is not normally subject to any type of enhancement.
Imitations
Tsavorite garnet has never been synthesized, but a number of imitations exist. These include green glass and green YAG. Green glass is also common at the mines in various rough forms.
Properties
of Tsavorite Garnet
|
Tsavorite
Garnet (a variety of grossular garnet) |
Composition |
Ca3Al2(SiO4)3 |
Hardness
(Mohs) |
7
to 7.5 |
Specific
Gravity |
3.60–3.68 |
Refractive
Index |
1.740;
Singly refractive |
Crystal
System |
Cubic |
Colors |
Light
to deep green |
Pleochroism |
None |
Dispersion |
0.028 |
Phenomena |
None |
Handling |
Ultrasonic:
generally safe, but risky if the gem contains liquid inclusions
Steamer: not safe
The best way to care for tsavorite garnet is to clean it with warm,
soapy water. Avoid exposing it to heat or acids |
Enhancements |
Generally
none |
Synthetic
available? |
No |
Further Reading
Tsavorite by
Peter Bancroft
The Collector Gem Buying Guides
In addition to the above, please visit the Learning
Vault at Palagems.com for many additional articles on gems, minerals and mining.
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