In today’s blog, Helen gives a background on Aquamarine, a beautiful stone that ranges in colour from green to a blue. It is the gemstone for March and is traditionally believed to protect sailors and and all those who who travel by water, as well as enhance open communication.
Aquamarine is a variety of the mineral Beryl (Beryllium aluminium silicate). The colour of ranges from green to bluish green to blue, with the intensity of blue varying from almost colourless to deep intense blue. It is interesting to note that the Beryl mineral group includes some of the finest gem varieties such as emerald, heliodor and morganite. The colour of Beryl is determined by trace impurities of different metal ions being present in the Beryl crystal lattice. Ferrous iron is (Fe 2+) is the impurity in aquamarine and which causes it to have a blue colour.
The majority of aquamarines are now sourced from Mozambique, Zambia, Pakistan and Nigeria. Historically Brazil was the world’s largest producer of aquamarine but recent tightening of Brazilian employment and environmental legislation has made it more expensive to mine there and so most gem quality aquamarines now come from east Africa. Geologically, aquamarines are found in pegmatites, the coarse textured crystal accumulations found in major igneous intrusive rocks.
If ethical sourcing of gems is important to you, then Brazilian aquamarines should be your preference. The miners will have been paid decent wages, their work environment will have been reasonably safe, and government agencies will have ensured that environmental damage from mining activity was minimised. I am certain that the same cannot be said for aquamarines sourced from elsewhere.
Aquamarines are highly prized for their colour, the deeper and more intense the better. Pastel aquamarines (the ones we tend to see on the UK high street) are many times less expensive than those stones that are a strong or deep blue and greenish blue. They are often heat treated to remove the greenish tint, and most modern production is routinely treated this way. For me, a sea green aquamarine is the most beautiful colour of them all, but commercially, deep blue (without any green at all), is the most expensive.
One of the cleanest gemstones – a gemstone with very few natural blemishes or imperfections - aquamarines can be cut as very large gems. Customers often request large aquamarines to be set in rings, but this can be problematic as to ensure optimum light reflection from the back facets of the cut gem, the gemstone may be very deep and the resulting ring will stick out high above the finger, making it uncomfortable to wear.
Over the last three years aquamarines have seen a dramatic rise in prices. It used to be that I could buy top quality stones for £50/carat. Now I would expect to pay in excess of £300/carat for similar stones. Chinese buyers, who particularly revere flawless gems, have recognised this feature of good aquamarines and have pushed prices up. That being said, many aquamarine stones have beautiful inclusions and I like to make jewellery that highlights and accentuates the shimmering natural internal features of some large gems.