Aquamarine, whose name is taken from the Greek for “sea water”, is the blue to greenish-blue variety of Beryl, a Beryllium Aluminium Silicate.
Beryl occurs in six colours, the others being green Emerald, pink Morganite, yellow Heliodor, colourless Goshenite and the very rare red Bixbite.
The primary sources of gem quality Aquamarine are Minas Gerais in Brazil, northern Pakistan,
the Ural mountains in Russia, Nigeria, Angola, Mozambique, Malawi, Kenya, Tanzania and Zambia.
It most commonly occurs in granitic pegmatites, but is also found in mica schists and limestone.
Aquamarine frequently occurs as very large crystals, but these are seldom of gem quality. The largest Aquamarine of cuttable quality was found in 1910 in Minas Gerais. It weighed 243 lb.
Chemical Formula: Be3Al2Si6O18
Crystal System: Hexagonal
Hardness: 7.5 – 8 (between Quartz and Topaz)
Specific Gravity: 2.72
Refractive Index: 1.577 – 1.583
Diaphaneity: Transparent to Opaque
Aquamarine is sometimes heat treated to remove unwanted greenish overtones in a stone, particularly for the American market.
The cheaper blue Topaz is occasionally substituted for Aquamarine, although a trained eye can easily tell the difference between the two stones.
Synthetic Aquamarine is being produced in Russian laboratories by the hydrothermal method, although it has not yet become prevalent on the market. Simulants are seldom encountered, as Aquamarine is not an easy stone to simulate.