The gemstone aquamarine (whose name means "sea water") is a transparent variety of the mineral beryl, valued since antiquity. Its color, by definition, is pale to medium blue or green, and blue and green are commonly both present in the same stone. Aquamarine is normally heated in order to transform green shades to blue, a process that is considered legitimate by gemstone dealers and jewelers worldwide due to the fact that it has been practiced since antiquity. Heating an aquamarine "drives out the green" but does not change the intensity of the stone's color.
In the past, darker shades of "aqua" have always been preferred, but softer lighter aquas have become far more fashionable in the last decades since the unfortunate influx onto the European and American markets of inexpensive Brazilian topazes which have been transformed from colorless to blue by artificial irradiation. (Topaz can be distinguished from aquamarine even in the dark: topaz "feels" cold.)

Aquamarines crystallize in boat-shaped bodies of coarse-grained rocks called pegmatites. In Kenya most of the aquamarine-producing pegmatites have been found in ancient rocks that had until recently been covered by lavas flowing east from Mount Kenya. These rocks are relatively unweathered and are very hard. As a result, many aquas are broken during extraction and few large Kenyan stones reach the market. Transparent apatite, a gemstone which is too soft to be worn in jewelry, is commonly found in the same deposits, as well as impressively large masses or sheets of white muscovite mica. Yellow or golden gem beryl in a surprising range of shades is also found in such deposits but infrequently.
Northern Tanzania has produced few aquas to date but good stones from further south are often brought to our buyers.

Our aquamarines

There are very few aquamarines in Tanzania. Furthermore, these aquamarines are usually quite pale, yellowish and included. However, aquamarines from Mozambique can be very nice. The rough we buy in our Mozambican office is either exported to cutting factories or faceted in our workshop. The aquamarine sold online are cut in our workshop. These aquamarines did not need any heating. They were naturally (unless specified otherwise) blue and usually nicely saturated in the rough.

Chemistry: Be₃Al₂Si₆O₁₈
System: Hexagonal
Hardness: 7.5
Density: 2.67-2.745
Ref. Index: 1.577(+-.016), 1.583 (+-.017)
Pleochroism: dichroic

Aquamarine on the Internet:
View aquamarine on mindat.org
Aquamarine on the ICA website
L'aigue-marine sur le site de l'ICA

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