The official birthstone for March, aquamarine, is one of nature’s wonders that reminds of transparent waters lapping the white sandy shores of the Caribbean islands. It is a semi-precious gemstone that comes in endless shades of blue and can be a beautiful addition to any jewellery collection.
Aquamarine Origin and Formation
Aquamarine is the light blue to the deep dark blue and greenish-blue variety of beryl mineral group. The name aquamarine comes from the Latin “aqua”, meaning “water”, and “marina”, meaning “of the sea”, as the colour of this beautiful gemstone reminds calm sea waters lapping the white sandy island shores.
Aquamarine has been used in jewellery for at least 3000 years with references in Roman, Greek, Egyptian and Sumerian writings. However, at that time, the gemstone was called “sea-green beryl”. The earliest known use of “aquamarine” in connection with the gem was in Anselmus de Boodt’s gemological work Gemmarum et Lapidum Historia (History of Gems and Stones) published in 1609.
Aquamarine, similar to other beryl family gemstones, forms within igneous rocks (pegmatites) under heat and pressure for hundreds of millions of years. Pegmatites are formed during the final stage of magma crystallisation. When magma under the earth’s crust interacts with mineral-rich rocks, they heat up and form gemstones. Pure beryl is colourless; however, if it interacts with minute quantities of iron, colourless gemstone turns into enchanting blue and produces aquamarine.
Aquamarine is found worldwide, with the largest deposits in Minas Gerais mines of Brazil. Other aquamarine deposits are located in Pakistan, Kenya, Zambia, Nigeria, Madagascar, Mozambique, China, Myanmar, Russia, Ukraine and the United States.
Aquamarines can be found in a range of colours, from pale and light blue to deep dark blue, greenish-blue and green-blue. As the name suggests, the best aquamarine colours remind of clear seawater, and the more translucent the stone, the more attractive it is considered.
In general, the purer and more intense the blue colour, the more valuable the stone, meaning dark blue and slightly greenish-blue gems are the most valued. Another important factor is the evenness of the colour, which should be consistent throughout the stone with no visible colour zoning.
The most valuable and sought-after aquamarine is a uniquely saturated blue Santa Maria gemstone mined in Santa Maria de Itabira, Brazil. However, today the term “Santa Maria” no longer refers to the origin as most of the Santa Maria de Itabira mines have been exhausted. Instead, it refers to aquamarines featuring similar colours to those originally mined in Santa Maria de Itabira. Another expensive vibrant blue aquamarine is the Double Blue, recently discovered and mined in Madagascar.
Aquamarine is a pleochroic gem, meaning it can change colour dramatically when viewed from different angles. It is visible in deeply coloured stones where the colour can alter from deep blue to almost colourless.
Most of the aquamarine available on the market is heat-treated to give it more of pure blue colour; however, naturally occurring blue gemstones are more valuable.
Aquamarine Clarity and Cut
Part of the aquamarine charm is its high clarity. Almost all aquamarines available on the market are eye-clean, meaning they are free of inclusions and blemishes.
Clarity is important with transparent and light stones. For this reason, the gems with visible inclusions are often cut into cabochons, beads or fancy carvings. If crystals contain enough liquid-filled inclusions, they are cut into cabochons to show a cat’s eye effect.
In general, aquamarines can be cut into almost any shape; however, they are often fashioned into round, oval and emerald cuts. Aquamarine can also be cut into a variety of freeform shapes, which are used for all types of designer jewellery, as well as one-of-a-kind ornamental objects.
Fashioned aquamarines often have to be quite large (5 carats >) to show dark, intense colour. However, smaller gems from Nigeria, Madagascar and Mozambique are known for their intense colour in sizes under 5 carats. This is the reason why smaller top-colour aquamarines may sell for more per carat than larger stones of the same colour.
Aquamarine Care and Cleaning
Aquamarine is a durable semi-precious gemstone, 7.5 to 8 on the Mohs hardness scale, meaning it is scratch resistant. However, it is always recommended to remove your aquamarine jewellery before household cleaning since this gem is sensitive to chemicals such as ammonia, alcohol and other acids.
Always remember that aquamarine is sensitive to direct sunlight. If exposed to the sun for a too long period, the colour of the gem can significantly fade, and this cannot be reversed. The same is true for prolonged exposure to heat.
To clean aquamarine at home, use mild dishwashing soap liquid and warm water. Carefully place your gemstones in the liquid and soak them for about 10 – 15 minutes. This will help to loosen any dirt. After the soaking, use a soft toothbrush to remove the dirt. Next, rinse out your piece of jewellery with clean water and dry it with a soft and lint-free cloth.
Ultrasonic cleaners are not generally recommended. Steam cleaners should never be used to clean aquamarine, as this gemstone should not be subjected to high temperatures.
When storing aquamarine jewellery, keep it separated from other softer gemstones to protect them from being scratched. Similarly, you will want to protect your aquamarines from harder gemstones such as diamonds, meaning it is a good idea to store aquamarine in individual cloth jewellery bags.
|Chemical Name||Aluminum beryllium silicate|
|Colours||Light-blue to deep dark blue, greenish-blue and green-blue|
|Hardness||7.5 to 8 on the Mohs scale|
|Refractive Index||1.564 - 1.596|
|Specific Gravity||2.72 (+0.18,-0.5)|
|Transparency||Transparent to opaque|
|Birefringence||0.005 - 0.009|
|Cleavage||Imperfect, basal, almost never seen|
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