The blue hues common to this beautiful stone are fitting considering the Latin aqua mare means ‘water of the sea’. Legends describe it as the mermaid’s stone, bringing luck to sailors and protecting them from the perils of the ocean.
A member of the beryl family, including emerald, heliodor, morganite and goshenite; aquamarine is distinguished by its blue to green colour.
Read more: Exploring the wonders of Myanmar
Many aquamarines available in the gem market have been heat treated. Starting with a yellowish, greenish or bluish-green beryl, heat treatment leads to a stable blue colour.
Where is Aquamarine Found?
Mainly found in mines in Africa and Brazil, the March birthstone can also be mined in Australia, China, Myanmar, Pakistan, Madagascar, Russia, USA and Sri Lanka. The trace amounts of iron found in aquamarine causes the sea like colour and is what distinguishes this stone from pure colourless beryl.
Distinguishing Features of Aquamarines
Aquamarine often occurs as a hexagonal-shaped long prismatic crystal, with striations and rectangular etch marks occasionally found on the prism surfaces.
The stone’s durability and bountiful supply make this stone a popular choice and it can be fashioned into most cuts, making it a firm favourite with many lapidaries.
Although many cut aquamarines are free of inclusions, two-phase inclusions (liquid and gas filled), spiky cavities and tubes parallel to the length of the crystal that look like rain are common.
The Dom Pedro Aquamarine
Perhaps the most famous aquamarine specimen is the 10363 ct Dom Pedro, which weighs an astonishing 26 kg. To this day, it holds the honour of being the largest piece of aquamarine ever to be cut. It was specialists in Idar-Oberstein, Germany, who took on the challenge in 1992.
Discovered by three Brazilian miners in Pedra Azul, Minas Gerais in Brazil in the late 1980s, the original aquamarine was a meter-long. Accidentally dropped it fractured into three pieces and the Dom Pedro was the largest piece from the split.
In 1991, Jürgen Henn from Idar-Oberstein, visited the owner of the large aquamarine crystal. However, the crystal was not for sale and he returned to Germany. In 1992 the stone went on the market and Jürgen asked his colleague Bernd Munsteiner to look at the stone. Bernd sent his son, Tom Munsteiner and Jürgen’s son Axel Henn, to strike a deal in Brazil and bring the stone to Germany.
For a year Bernd worked on the stone, studying the crystal, drawing facet patterns, cutting, faceting and polishing. Before transforming the rough stone into the majestic obelisk, recognised and admired by many today.
The Dom Pedro first went on public display in 1993 at Basel, the annual gem fair in Switzerland. Almost cut up into smaller gemstones in the late 1990s, it was rescued by Jane Mitchell and generously donated to the Smithsonian, National Museum of History, Washington DC, USA. The awe-inspiring gemstone is in the permanent collection of the museum, housed in the National Gem Collection Gallery.
When viewed through a Chelsea colour filter aquamarine give a blue-green colour; different from the reaction of many of the other light blue gemstones. When tested with a dichroscope a blue/ green colour shows colourless and pale blue. The material is dichroic. ■
Interested in finding out more about gemmology? Sign-up to one of Gem-A's courses or workshops.
If you would like to subscribe to Gems&Jewellery and The Journal of Gemmology please visit Membership.
Cover image beryl aquamarine crystal. Photo credit Pat Daly.