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The name "garnet" comes from the Latin granatus ("grain"), possibly a reference to
and color to some garnet crystals.
Garnets are most commonly red in color but can be found in a variety of colors,
including purple, red, orange,
yellow, green, brown, black, or colorless. Hardness is 6.5-7.5, specific gravity is
3.1-4.3, luster is vitreous to
resinous, and they can be transparent to opaque. The lack of a blue garnet was
remedied in 1990s following
the discovery of color-change blue to red/pink material in Bekily, Madagascar but
these stones are very rare.
Color-change garnets are by far the rarest garnets except uvarovite, which does not
come in cuttable sizes. In
daylight, their color can be shades of green, beige, brown, gray and rarely blue, to a
reddish or purplish/pink
color in incandescent light. By composition, these garnets are a mix of spessartine
and pyrope, as are Malaya
garnets. The color change of these new garnets is often more intense and more
dramatic than the color change
of top quality Alexandrite which is frequently disappointing, but still sells for many
thousands of U.S. dollars
per carat. It is expected that blue color-change garnets will match Alexandrite prices
or even exceed them as
the color change is often better and these garnets are much rarer. The blue
color-change type is mainly
caused by relatively high amounts of vanadium (about 1 wt.% V2O3).
Six common varieties of garnet are recognized based on their chemical composition.
They are pyrope,
almandine or carbuncle, spessartite, grossularite (varieties of which are hessonite or
cinnamon-stone and
tsavorite), uvarovite and andradite. The garnets make up two solid solution series; 1.
pyrope-almandine-spessarite and 2. uvarovite-grossularite-andradite.
Garnet is the birthstone for January, and has been used since the Bronze Age.
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