Aquamarine is a light blue variety of the mineral beryl. Being the
principal mineral of both aquamarine and Emerald, as well as several
other gem types, Beryl is considered one of the most important gem
minerals. By definition, aquamarine is light blue to a clear and pale
light green, with the color due mostly to traces of iron in the
structure. If it does not have any discernable blue to greenish
color, but is truely white, then it is just white beryl, not the
aquamarine variety of beryl. The formal name for the colorless
variety is goshenite beryl. It’s the blue color that makes that piece
of beryl an aquamarine. However, it should be noted that a truly
clear piece of beryl is actually fairly uncommon. Most material has
at least a trace of bluish, greenish, yellowish, or pinkish cast to
it. Aquamarine in it’s best colors can be a quite vibrant almost
medium shade of… well, it’s still a light blue. But a lot of
aquamarine, especially the cheaper to cheapest grades, are very pale
indeed. Pricewise, the darker and more intense the color, the better
and more costly the stone. Good aqua should also be generally without
eye visible inclusions. Very pale or almost colorless aquamarine is
generally very cheap indeed.
In it’s purest form, the mineral beryl (a beryllium/aluminium
silicate) is clear/white/colorless. It can be colored by a number of
impurities/trace elements, usually as their oxides replacing the
beryllium in the structure, which then give rise to a range of
different colors. The most famous of these is emerald, where the
beryl is colored green by traces of Chromium and sometimes a tad of
Vanadium. Iron can also induce a pale green color, but of low
intensity. Normally iron produces at least a bluish green color, and
heat treatment of any of these usually changes the oxidation state of
the iron in the structure to permanently change the color of the stone
to mostly light blue. This is the form most aquamarine seen in the
market is in. As mined, it’s often greener.
If the beryl is colored instead, by traces of manganese, then it gets
a pink/rose/peach color range, and is known as morganite. One source,
in Utah, produces a manganese colored variety of beryl where the color
is dark enough to be called red, though the stones are generally small
and flawed. It’s called bixbite.
And a pale to lemon yellow ranging to rich golden yellow colored
variety, also mostly due to iron in the structure, is called heliodor.
Peter Rowe G.G.