Some gemstones belong to beryls: besides emerald, it is also aquamarine, bright heliodor and gentle morganite.
Chrome and vanadium, containing in emerald, give it the bright colour which is not fading at heating and under the sun beams. The colour of emerald is different, depending on the extraction place. Little bit bluish-green dense colour is the most claimed.
Colombian emeralds have a pure green colour with a weak bluish shade. They are dichroic, that means, that a colour has two axes and changes from a sight corner. The Colombian emerald dominated in the market during many years. Brazilian emeralds, in comparison with Colombian, are lighter and have a yellowish shade. The stones from Zambia have a dark emerald-green colour, and they have an excellent transparency.
It is a lot of absolutely “pure” emeralds. Quite often they have inclusions in the form of fibers or rods of tremolite, internal cracks or rough colour distribution. Internal pressure makes emeralds very sensitive to squeezing. The emerald cutting has been specially developed to leave the maximum weight of the precious stone and to strengthen its colour. It is a cutting, at which the corners are left to avoid the breaking off or cracks formation.
Estimation of emeralds
The most important criterion in the estimation of emeralds is the intensity of the colour. Because of the rarity of the big pure deep green emeralds, their price can practically be even to the cost of similar diamonds. Ideality of the colour dominates at the estimation of emeralds: if the colour of the stone is darker or lighter, the price is reduced. The transparency and the size are two more factors of the estimation. Emeralds of the lower grade are used for a cutting in cabochons or on beads.
Hardness 7,5 – 8 on Moos scale.
Density from 2,69 to 2,80
Factor of refraction from 1,57 to 1,59
Crystal lattice: beryl has a six-angle prism structure. It is found in garnets and pegmatite and also in the alluvial deposits. It has a glassy shine.
Deposits of emeralds: the best stones are in Colombia, Zambia and Brazil. They are also found in India, Australia, Pakistan, Russia, the South America and the USA.