Aquamarine is a pale-blue to light-green variety of beryl.^[2] Greenish-blue aquamarine can be changed to pure-blue by heat.^[3]

The aquamarine has a chemical composition of Be₃Al₂Si₆O₁₈,^[4] also containing Fe²⁺.^[5] It has a hardness of 7.5 to 8.^[6] Aquamarine contains no or little noticeable inclusions.^[7] But it can have inclusions like mica, hematite, or salt-water.^[8]

Aquamarine is a common gemstone.^[9] However there is a rarer variant of aquamarine called maxixe which is deep blue in color,^[7] but its color can fade due to sunlight.^[1] The color of maxixe is caused by NO₃.^[10] Dark-blue maxixe color can be produced in green, pink or yellow beryl by irradiating it with high-energy particles (gamma rays, neutrons or even X-rays).^[11]

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