Aquamarine

Aquamarine ( Latin-water of the sea) is so named because of its seawater color. A dark blue is the most desired color. The coloring agent is iron. Lower qualities are heated to 400-450 degrees C to change them to the desired, permanent aquamarine blue. Higher heat will lead to discoloration. Care must be taken when making jewelry Color can also be improved with neutron and gamma irradiation, but these changes do not last. Aquamarine is brittle and sensitive to pressure. Inclusions of fine, oriented hollow rods or aligned foreign minerals rarely cause a cat's-eye effect or aster-ism with six-ray stars with a vivid sheen.

Deposits The most important deposits are in Brazil, spread throughout the country. The well-known deposits in Russia ( the Urals ) seem to be worked out. Other deposits of some commercial significance are in Australia ( Queensland ), Burma ( Myanmar ), China,  India, Kenya, Madagascar, Mozambique, Namibia, Nigeria, Zambia, Zimbabwe, and the United States. The host rock is pegmatite  and coarse grained granite as well as their weathered material.
The largest aquamarine of gemstone quality was found in 1910 in Marambaya, Minas Gerais (Brazil). It weighed 243 lb ( 110.5kg ), was 18 in ( 48.5 cm ) long and 15.5 in ( 42 cm ) in diameter, and was cut into many stones with a total weight of over 100,000 ct. There have been finds weighing a few tones, but these aquamarines are opaque and gray, not suitable for cutting.
The preferred cuts are step ( emerald ) and brilliant-cut with rectangular or long oval shapes. Turbid stones are cut en cabochon ore are used for necklace beads.

Possibilities for Confusion with eudase, kyanite, topaz, tourmaline, zircon, and glass imitation. Synthetic aquamarine can be produced but is uneconomical. The "synthetic aquamarine" sold in the trade is really aquamarine-colored synthetic spinel.