Garnet Information
The gemstone Garnet is the official birthstone for January. It is also the stone for the Zodiac sign Aquarius.
Garnet may be given as a gem on the 2nd and 6th wedding anniversary.
Garnet occurs in every color
except blue and most
varieties are named for their color. Rhodolite is a purplish red,
hessonite is the name for an orange, cinnamon, or pinkish variety.
Tsavorite is the name given to dark green grossularite. Uvarovite and
demantoid are also green varieties.
Pyrope garnets are purplish red, orangy red, crimson, or dark red.
Spessartite garnets range from yellow and orange through red to reddish
brown to dark black/brown. Color change garnets exhibit a
"alexandrite-like" effect when viewed in natural light or artificial
lighting.
Garnets range from a 7.0 to 7.5 on the Mohs scale of hardness and are
found in the U.S. (Arizona), South Africa, Argentina, Australia,
Brazil, Myanmar (Burma), Scotland, Switzerland and Tanzania . Garnets
are formed when high temperatures and/or pressure is a factor and
geologists often use garnets as a gauge of the amount of temperature
and pressure that was present during their formation.
Garnet's powers include healing, strength, and protection and
it is
often worn to relieve inflammations of the skin. It is also believed to
regulate the heart and blood flow and aid in curing depression. In
earlier times, garnets were exchanged as gifts between friends to
demonstrate their affection for each other and to insure that they meet
again.
Almandine
garnet
(Fe3A12Si3O12), has an isometric crystal system with a refractive index
of 1.75 -1.83 and a hardness of 7 - 7.5 on the Mohs scale. The specific
gravity is 3.95 - 4.30.
One of the classic sources of this
garnet is Alabanda, in Asia Minor. Its common name is a variation of
the source. The Roman historian Pliny wrote of this type of garnet. Our
common, dark red garnets are a
blend of almandine and pyrope. Throughout history, this has been one of
the most popular gems. They are found world wide and in great
abundance, therefore the value is low. Very large crystals exist, but
because
of their dark tone, only small to medium sized gems are faceted. These
are cut very shallow, to let light pass through. Almandine garnets from
Idaho and India
sometimes have asbestos fiber inclusions. These will produce star
stones when properly cut. They are highly prized by collectors, because
of their rarity. They are also one of the most difficult gems to cut.
.Hydrogrossular
garnet (Ca3A12(SiO4)3-x(OH)4) has an isometric
crystal system with a refractive index of 1.72 -1.80 and a hardness of
6.5 - 7.0 on the Mohs scale. The specific gravity is 3.40 - 3.70.
Hydrogrossular differs from the other
garnets in that it is never transparent. It ranges from translucent to
opaque. The most common color is a bluish green, but it is also
found in pink, white, and gray. Because of its coloring and
translucency, hydrogrossular is sometimes used as a jade substitute.
Large
pieces are available, which make carvings possible.
Experts say the
name
rhodolite comes from the Greek word, rhodon, meaning rose. Other
scholars compare the name to rhododendron. In either case, the name is
comparing the color to a flower.
Malaia is a
Bantu word
that means out of the family, or out of the tribe. It is also used to
mean prostitute or deceiver. It came into usage for a number of garnets
that did not fit into any of the standard categories.
Dematoid comes
from
the French, “demant,” meaning diamond. The reason is obvious, with its
high brilliance and dispersion. Dematoid garnets are a green variety of
andradite. They are known for their golden, “horsetail” inclusions.
Tsavorite
is
named
after its only source, the Tsavo Valley in Kenya. It is the chromium
colored, green variety of grossular. These popular gems demand high
value
in today’s market. While faceted stones approaching 20 carats are
known, their deep coloring usually keeps their size below three carats.
Hessonite is
from a
Greek word meaning inferior. This refers to it having less hardness
than other garnets. Hessonites are an orangish variety of
grossular garnet. Sometimes their coloring leans towards the
pink.
Asbestos, Quebec is one of the most common sources. The miners find
pinkish orange crystals among the asbestos. Africa is also a major
source for hessonite.
Any
gem that changes color is a rare
find and a treat for collectors. Garnets exhibit the widest variety of
color changes in the gem world, with almost every hue exhibited.
It is commonly said that garnets come
in every color of the rainbow except blue. This is still true in
natural light, but there are recent discoveries of garnets that turn
blue in artificial light. Color change garnets are mostly pyrope
and spessartite in composition. Except for the color change, they are
identical in properties to the Malaia variety. Their primary source is
Africa. Idaho garnets, which are primarily
almandine/pyrope mixtures, occasionally show a strong color shift from
red to purplish red.
In
Greek mythology, Proteus was a sea
god, capable of changing his shape. It has become a noun for one who
easily changes their appearance or principles. Proteus are the only
treated garnets.
All the others resist change, but a few almandine/pyropes from the US
will change into Proteus. The treatment brings a thin layer of metals
to the surface. This causes it to have a dual
appearance. In reflected light, they have a dark gray, metallic luster,
much like hematite. In transmitted light, the dark red of the garnet
shows through.