Aquamarine gemstone is one of nature’s wonders that reminds of transparent waters of the ocean. Even the name of this clear stone comes from the Latin “aqua”, meaning water and “marina”, which means “from the sea”. When you look at these beautiful gemstones, you imagine calm sea waters lapping the white sandy shores of Caribbean or Pacific islands.
Aquamarine Origin and Formation
They can be found in pegmatite rocks’ cracks and fissures. Almost all aquamarines are formed in pegmatites.
Pegmatites are formed during the final stage of magma crystallisation. When magma under the earth crust interacts with mineral-rich rocks, they heat up and form the gemstones. Beryl crystals with a touch of chromium give emeralds, manganese gives morganites and a touch of iron produces aquamarines.
Aquamarines can be found around the world where there are mountains. However, this doesn’t mean that they are easy to find. In fact, only 0.003% of all magma rocks contain beryl-rich pegmatites.
The majority of aquamarines are mined in Minas Gerais, Brazil. These beautiful “water clear” stones are also sourced from mountains of Pakistan and southern Asia. Actually, they supply the world with some of the finest quality gemstones.
Other sources of aquamarine are Kenya, Nigeria, Zambia, Madagascar, Mozambique, China, Myanmar, Russia, Ukraine, and the US.
Aquamarines can be found in a range of colours from pale and light blue to deep dark blue and greenish-blue. As the name suggests, the best colours of aquamarine are those that remind of the clear seawater and the more translucent the stone is (like blue lagoon), the more attractive it is considered.
The intensity of the colour is important with dark blue and greenish-blue stones. Intense colours are more valued. Another important factor is the evenness of the colour, it should be consistent throughout the stone with no visible colour zoning.
The most valuable and sought after aquamarine is a uniquely saturated blue the Santa Maria gemstone, originally mined in Santa Maria de Itabira in Brazil. The term “Santa Maria” can also refer to the same colour aquamarines from anywhere.
It worth mentioning that aquamarines can change colour dramatically when viewed from different angles (pleochroism). This is really visible in deeply coloured stones where the colour can change from deep blue to almost colourless.
Part of the aquamarine charm is its high clarity. Almost all aquamarines in the market are eye-clean, meaning they are free of inclusions and blemishes.
Clarity is extremely important with transparent and light blue stones.
Stones that have visible inclusions are often cut into cabochons or fancy shapes.
The price of aquamarine is mainly determined by its colour.
The most valuable colours are dark blue, or slightly greenish blue, and the richer the blue the better.
Since aquamarines are usually clean to the naked eye, you should avoid the stones that have a lot of inclusions and blemishes.
Another price determinant is high transparency of the stone, which also influences the cut of aquamarines. Being highly reflective gemstones, aquamarines maximize the sparkle when being cut into emerald or other step cuts. Poor cut quality will lower the value.
Aquamarines can be found in large sizes, but the price will still be made by colour and clarity. In fact, cutters cut out impure parts of the rough, to create a smaller, strongly coloured, clean stone. A small high-quality stone will be worth a stone twice its size if it is pale and with flaws.
Cover image credit: Rob Lavinsky