Everyone is familiar with emerald, one of the four traditional precious gems. But many people don't realize that emerald is a member of a notable gemstone family, beryl. The other, less famous, beryls include aquamarine, morganite, golden beryl and bixbite.
It's fair to say that the delicate blue-green aquamarine is the second most famous beryl, though not the rarest. Bixbite, the red beryl, is extremely rare and is found in only a few locations in Utah and New Mexico in the USA. Aquamarine is found in most locations where ordinary beryl is found, including Brazil, Australia, Burma, China, India, Kenya, Madagascar, Mozambique, Namibia, Nigeria, Pakistan, USA, Zambia and Zimbabwe.
Though aquamarine and emerald belong to the same family, they are surprisingly different. They are both beryllium aluminum silicates. Where emerald is colored by trace amounts of chromium and and/or vanadium, aquamarine is colored by iron. But while emerald and beryl have essentially the same specific gravity and refractive index, emerald tends to be quite hazy and included, while aquamarine typically has excellent transparency and clarity.
Though the beryls are quite hard gems -- rating 7.5 to 8 on the Mohs scale -- emerald has always been regarded as a somewhat delicate gem due to its many inclusions. Emeralds are usually oiled to fill fractures and improve their color. Aquamarine, on the other hand, requires no special treatment and is suitable for all kinds of jewelry, including rings.
The intensity of color and the clarity of the stone are the most important criteria when evaluating aquamarine. Deep blue aquamarines are rare and command higher prices in the world's gemstone markets, though deep blue aquamarine is still a pastel blue. The darker shades of aquamarine are often heat treated to improve the color. Unlike other gems, aquamarine is not diminished by lesser intensity of color -- many people actually prefer the more crystal clear lighter gemstones to the richer, deeper colors. You will find aquamarine in both faceted and cabochon cuts.
Aquamarine derives its name from the Latin term for seawater, and has a long tradition as the sailor's lucky stone. The Greeks and the Romans knew the aquamarine as the sailor's gem, ensuring the safe and prosperous passage across stormy seas. Legend has it that aquamarines were the prized possessions of mermaids and thus would would protect sailors from danger, including warding off sea sickness.
Aquamarine is the birthstone for March.