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Almandine
is the deep-red iron rich garnet and often cut into ovals. If the stone is
deep it may appear too dark and has less value. Much of the older Victorian
jewelry used these garnets.
Pyrope is a fiery red
garnet, but it too may suffer from being too dark. Large stones are often
available but it is not one of the more highly priced gems.
"Rhodolite" is a
special variety of the Almandine-Pyrope mix. It is about 1/2 way between the
two end members and is a reddish-purple stone usually with good clarity. It
is very popular today, and is among the more expensive of the red garnets.
It is still not in the price range of good imperial topaz, aquamarine or
good tourmalines. It is a second tier stone.
Spessartite is a
manganese rich variety that may be orange to orange-brown in color and large
stones are usually not available. It is priced above Almandine and Pyrope
and about the same level as rhodolite.
Grossular garnets
come manly in a yellow color from Sri Lanka. It also comes in a yellow-brown
variety with the name "Hessonite" (from the Greek "esson", meaning
inferior). Today the most prized member of the garnet family is the green
grossular garnet called "Tsavorite" from near the Tsavo National park in
Kenya. This green garnet gets it's color from chromium just like emerald. It
is sold as an emerald substitute and brings a quality price. Large stones
above 3 carats are very uncommon.
Andradite garnet is
usually black and of no interest to the gem trade, but one variety called "Demantoid"
is a lively green. It is a little on the softside and very brittle so it
needs good protection in jewelry. It brings a premium price, but is
available only in small stones.
Uvarovite rarely
occurs in facetible sizes, but when it does it makes a spectacular stone. If
it is emerald green in color it can bring a hefty price. If too dark, it not
worth nearly as much.
The garnets comprise a family of complex silicates with widely varying
chemical composition but similar structures. While everyone is familiar with
dark brownish or purplish red garnets, many are unaware that garnets can
occur in almost any color except blue
Demantoid Garnet
Demantoid garnet is a rare and beautiful bright grass green sub-variety of
andradite garnet. It appears to have first been discovered around 1892 in
the Bobrovka area of Russia.
The Bobrovka is a small tributary of the River Tschussowaja in the Sissersk
region on the western side of the Ural Mountains.
It was at first thought to be emerald, which is found nearby, and has been
erroneously called "Uralian emerald".
The name demantoid means diamond-like, because it has a very high adamantine
lustre, and a color dispersion higher than diamond. The only disadvantageous
property of demantoid is its low hardness figure at about 6.5 Moh. It is the
softest of the garnets, and is more suitable for use in brooches, pendants,
or ear-rings, rather than rings, because of this.
The brilliant color of demantoid garnet is due to partial replacement of the
silicate by chromic oxide.
A diagnostic characteristic of demantoid is the inclusion of radiating
fibers of byssolite (asbestos) fibers in a pattern described as a
horse-tail. There is no other green stone which shows this feature.
In late Victorian times, and early in the twentieth century, demantoid
became a very sought after stone. It commanded high prices because it has
never been available in large quantity. In recent decades, it has been
unobtainable as newly mined stones, and has only been available from antique
jeweler.
Recently, small finds have again been made in Russia, and a small quantity
of fine quality stones have recently come onto the market.
Gemstone lovers wishing to acquire a piece of demantoid garnet should take
this opportunity to do so. If the current seams of demantoid run out, there
may be another century without new stocks of demantoid becoming available.
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The history of Garnet dates back to the Bronze Age (more than 5,000 years
ago), when it was a very popular gemstone. According to Christian and Jewish
mythologies, during the Great Flood a radiant red Garnet guided the way for
Noah, ultimately leading his ark to salvation. Garnets are available in a
wide range of "warm" tones such as reds, oranges, yellows and burgundies, as
well as greens and some rare color-change varieties.
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