A Dip In Aqua : Selecting the Correct Aquamarine
- Published
- in Gemstones
With the heat of summer now settling down and the monsoon transforming parched trees and grass into lush greenery, aquamarine with a slightly greenish blue colour seems to be the perfect gemstone to bring out the emotions of the season.
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| This designer cut Aquamarine weighs 10.73 cts. |
Aquamarine, a gem from the Beryl family is one of the closest cousins to the famous Emerald with both its chemical characteristics and its cool colours. Aquamarine gets its name from the words “aqua” meaning water and “mare” meaning sea which explain the colours of the stone. Unlike its highly included cousin, Aquamarines are relatively eye clean with the same hardness as emeralds at 7.5 to 8 on the Mohs scale. It’s fewer inclusions make it an easier gem to work with which is why you will commonly see Aquamarines cut in modern shapes with different carving patterns.
Clarity
Although Aquamarine has been noted to be relatively eye clean, I have personally seen beautiful Smokey Aquamarine stones with phenomenal colour. Although filled with growth tubes, hematite platelets and phase inclusions to mention a few, these smokey stones have a different aura to them, one that makes them appear almost mystical. Their growth tubes reflect light which can also result in a chatoyant band across the stone transforming them into the variety Cat’s eye Aquamarine.
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| Tubes reflecting light giving a chatoyant band |
Colour
Aquamarines are an inorganic gemstone which means they are derived from non-living organisms and are made of the elements beryllium, aluminium, silicates and oxides. The gem’s colour is brought about by the trace element iron, the same element giving Aqua its strong sea blue and highly valuable dark blue colour. These stones are mined from pegmatites in Brazil, Mozambique, Nigeria, Zambia, Madagascar, Afghanistan and Pakistan.
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| Dark blue colours of Aquamarine |
Treatments
Heating of the rough to improve the colour of the gem has become a norm in the industry and is accepted by the gem trade globally. These stones are also subjected to heat to improve the gems clarity and durability. For example, light green or yellowish green stones are heated to high temperatures for lengthy periods which alters the colour to a better marketable blue.
As a pleochroic gem you will see a green or a greenish blue colour in one direction of the stone. This means the stone is a doubly refractive stone and upon magnification you will see a slight doubling of facet junctions.
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| Brazilian Aquamarine |
As you perhaps know, I am always captivated by what each gemstone variety holds inside and Aquamarines with it’s myriads of inclusions have always caught my attention. Over time I have seen stones so clear its been hard to determine if the stone was truly an Aquamarine or not, and some with inclusions that are absolutely breathtaking.
Just to make it a little easier if you are buying Aquamarine and need to know what to look for, here are some of the points to keep in mind.
- As the gem is a DR stone, you will see slight Doubling at facet junctions, negating the option of Glass or Plastic, which will also be warm to touch
- The body colour of the stone should be Blue, slightly – medium – strong greenish blue
- Inclusions such as growth tubes, hematite platelets, black dendritic inclusions, 2-3 Phase inclusions are some of the inclusions
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| Reddish brown hematite platelets |
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| Growth tubes seen in Aquamarine |
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| Dendritic moss like inclusion |
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| 3 Phase inclusions in Aquamarine |