Aquamarine is a member of the beryl family and its colour can range from an almost translucent blue to intense blue-green or teal. Beryl also contains other gem varieties, including Emerald, and some lesser known varieties such as Morganite and Heliodor.
The most valuable aquamarines come from Brazil, but the gemstone is also mined in Kenya, Nigeria, Madagascar, Zambia, Tanzania, Sri Lanka, Pakistan, Afghanistan and Russia.
In the 19th century, sea-green aquamarine jewellery was the most sought after but, in later years, the colour preference shifted to a more intense blue. Light green Beryl can be transformed into Aquamarine if heated to 750º F (400º C). The green hues in most Aquamarine can also be removed through heat treatment.
Folklore, Legend, and Healing Properties:
Since early times, aquamarine has been believed to endow the wearer with foresight, courage, and happiness. It is said to increase intelligence and make one youthful. As a healing stone, it is said to be effective as a treatment for anxiety and in the Middle Ages it was thought that aquamarine would reduce the effect of poisons.
A legend says that sailors wore aquamarine gemstones to keep them safe and prevent seasickness.
Aquamarine is not only the birthstone for March, but also the gem given as a 19th wedding anniversary gift.
References: The Jewellery Editor
How to Find out More About Aquamarine:
The GIA encyclopedia is an excellent resource if you want to do a deep dive on Aquamarine.