A to Z of Gemstones: A: Aquamarine
Gemstone family: Beryl
Moh's scale of hardness: 7.5-8
About: Aquamarine is the bright blue variety of beryl species. Its colour can be pale to dark blue or greenish blue which is caused by iron trace elements. Aquamarine derives from the Latin words “aqua marina” which mean water of the sea. Depending on the transparency of the stone which can be anything between transparent to almost opaque, aquamarines are cut into faceted gems, cabochons, beads or carvings and occasionally rough crystals are left intact in their hosting rocks and sold as gorgeous rough specimens. Usually, aquamarines look clean when seen with the naked eye. A typical inclusion of the stone is what is known as “rainfall” consisting of parallel growth tubes.
Origin: The main sources of aquamarine are: Brazil, Pakistan, Myanmar, Namibia, Mozambique, Zambia, Kenya, China and the U.S.A.
Use in jewellery: Aquamarine’s lustre is vitreous; it rates 7.5-8 on the Mohs scale which makes it suitable for jewellery that has secure settings to protect the stone from wear.
Treatments, synthetics and imitations: The most common treatment for aquamarines is heating in order to enhance their colour and remove the yellow component to create a purer and more valuable blue. Synthetic aquamarines exist in the trade but they are not as common as other synthetic gemstones. They have the same chemical properties as natural aquamarines but their value is significantly lower so they should always be disclosed as synthetics. Materials that are most commonly used to imitate aquamarine are: treated topaz, synthetic spinel and glass.
Famous examples: The largest cut aquamarine in the world is the “Dom Pedro”, a 10,636ct obelisk –shaped stone. The stone was cut by the world famous gem artist Bern Munsteiner.