Although a Beryl Aquamarine as well as emerald fall under there own catogory of gem and are not grouped into the precious beryl group. Aquamarine is named afer the latin for seawater. The most popular colour is dark blue which is caused by iron being present when formed the best mine for this colour was santa Maria in Brazil and this top colour gem is sometimes known as this regardless where it came from. It is known for lower qualities to be heat treated to enhance the colour and in some case neutron and gamma radiation but this type of treatment is known not to last. Aquamarine is brittle and sensitive to pressure so great care must be taken when setting. It has a mohls hardness of 7.5-8 and a refractive index of 1.564-1.596