The corundum group consists of pure aluminum oxide.
Trace amounts of other elements such as iron, titanium and
chromium give sapphires their blue, yellow, pink, purple, orange or
greenish color. Sapphire includes any gemstone quality varieties of
the mineral corundum except the fully saturated red variety, which is
instead known as ruby.
Choosing
a Sapphire
The most valuable
sapphires have a medium intense, vivid blue color. The best sapphires
hold the brightness of their color under all different types of
lighting. Any black, gray, or green overtones mixed in with the blue
will reduce a stone's value. In general, a more pastel blue would be
less preferred than a vivid blue but would be priced higher than an
over-dark blackish blue color.
As with all
gemstones, sapphires which are "clean" and have few visible inclusions
or tiny flaws are the most valuable. However some very fine sapphires,
in particular those from Kashmir, have a velvety mist-like texture
which enhances the richness of the blue
Although we
have mostly talked about blue Sapphires many other colors are available. Some of
these are quite rare.
Color Change Sapphire
Sapphire is considered a Type 2
gemstone
Type 2 Description: Usually eye
clean with some inclusions under magnification
