Aquamarine gem

Chemistry: Be3Al2Si6O18 + Fe

Crystallography: Hexagonal

Refractive index: 1.567 - 1.590

Hardness: 7.5 - 8

Specific gravity: 2.66 - 2.80

Cleavage: Indistinct

Heat sensitive: No

Wearability: Excellent

Special care instructions: None

Enhancements: Maybe heat treated to remove green tint. Very common and undetectable.

Aquamarine is a member of the beryl family, as is emerald. 

Aqua is known for its blue or blue-green coloring, which accounts for its name. 

The legends behind aquamarine all have to do with the sea and water. 

It is a popular gem that wears well, is readily available and moderately priced. 

One of the most remarkable qualities of this gem is the sizes it is available in. 

Gemstones have been cut that weigh several hundred carats, way too large to be worn. 

The price is dependent on its clarity, the depth of color, and to a lesser extent, the purity of color.

Another interesting feature of this gem is its inclusions. 

Beryls and aquamarine, in particular, are known for having long, hollow tubes. 

This is a distinctive feature and will identify a gem as a member of the beryl family. 

Cat’s eyes or stars can be produced with proper cutting if there are enough of these hollow tubes. 

A cat’s eye aquamarine is a thing of beauty and is highly prized by collectors. 

Prices will be very close to that of a clean, faceted gem with the same coloring. 

Star aquamarines are even more uncommon than cat’s eyes and can demand a premium price. 

This beautiful gem receives its coloring from a trace of iron inside its structure. 

The color can be very light to moderately saturated. You will rarely see an aqua that is more saturated than a Swiss blue topaz, and when you do, the color is usually enhanced by the way they are cut.

There is a very dark blue aqua that came on the market about four decades ago, called the Maxixe aquamarine. 

(That is pronounced ma-she'-she.) 

This is an irradiated product, and the color isn't stable. 

These have mostly disappeared from the market, but if you are ever offered a very deep blue aquamarine, be cautious. 

Most aquamarines come out of the ground with a greenish tint. 

This will disappear, leaving a purely blue color by heating to 375 degrees Centigrade. 

Heating aqua to remove its green tinting is common and used to be done as a matter of routine. 

Now we have a more sophisticated public, and many of them are starting to appreciate the slightly green gems, knowing that they haven't been heat treated. 

This process is impossible to distinguish, so pure blue aquamarines are described as probably heat treated.

Beryls are some of the easiest gems to polish. 

The high quality of polish that gives light Aquas such exceptional brilliance is probably confused with higher refractive index (RI) gems. 

While they have moderate dispersion of .014, light stones with high crown angles will show their spectral colors well. 

This makes for an outstanding gemstone. 

While the highest values go to the richer colors, a well-cut, light aquamarine is one of the most spectacular examples of the gem world.