Aquamarine, is a pale-blue to light-green variety of the beryl family, with its name relating to water and sea.  The color of aquamarine can be changed by heat, with a goal to enhance its physical appearance (though this practice is frowned upon by collectors and jewelers).  It is the birth stone of March.  The sample you see here has not been altered by heat. 

Aquamarine's color is caused by trace amounts of iron found within the crystal structure. It can vary from pale to vibrant and transparent to translucent. Better transparency in aquamarine gemstones means that light may go through the crystal with less interference.

The value of aquamarine is determined by its weight, color, cut, and clarity.  Due to its relative abundance, aquamarine is comparatively less expensive than other gemstones within the beryl group, such as emerald or bixbite (red beryl), however it is typically more expensive than similarly colored gemstones such as blue topaz.