Aquamarine is an important variety of beryl gemstone.
Aquamarine color is nearly always a light blue and deep blue color is very rarely encountered. Greenish blue is also a very predominant color in aquamarine, but blue is the most desired color. Some aquamarines are heat treated to eliminate green tint.
Aquamarine is a very precious gemstone, though commercially not as precious as emerald or ruby.
Forming hexagonal (six sided) crystals is a similarity between emerald and aquamarine.
Aquamarine has become very popular because of very pleasing light blue color and excellent hardness (7 on Mohs scale) and is widely used in jewelry industry.