March 01, 2021
Emeralds gemstones & jewellery
A gemstone once prized by the Pharaoh Cleopatra and in the first century AD Pliny the elder stated that “nothing greens greener”; since then emeralds have certainly not lost their appeal.
Picture from Muzo Emeralds.
Emeralds are of the Beryl family, the same as aquamarine, which grows in long hexagonal prisms. Today, emeralds are found in Colombia, India, Siberia, South Africa, Zambia and Brazil, but the oldest known emerald mines in the western hemisphere were in Egypt. Colombian emeralds are highly prized, as a significant proportion of the best quality stones are discovered there. Emeralds from Colombia typically have three-phase inclusions (Solid, Liquid and Gas), which is a tell-tale sign of their origin.
As a mineral species emeralds are usually highly included (containing foreign minerals, or deformities within the mineral lattice), this is because they grow in hydrothermal veins where liquid from deep within the earth's crust bubble up towards the surface. The inclusions within an emerald are known as “le jardin”, as it looks like a garden and reflects the colour of new spring growth. When an emerald is found with relatively few inclusions, prices can sky-rocket.
When choosing an emerald, colour is undoubtedly the most important factor, they can have a bluish green tone or a yellowish green hue, which varies depending on their origin, and can vary within each deposit. A typical emerald is “bottle green” with medium-dark tone and high saturation, if there is little saturation and a light tone then the gem is classed as “green beryl”.
Image from GIA.
A significant percentage (over 95%) of emeralds are oiled which helps to improve their clarity. As members of the beryl family, they are formed with internal fractures and inclusions. Oils help to lower the relief of these inclusions and make them appear less, this is a normal and widely accepted procedure in the industry. A gemstone that comes with a certificate should tell you any treatments and to what extent.
Emeralds have a hardness of 7.5-8 on the mohs scale of hardness, the same as Sapphire, however the stone is brittle and can break along cleavage planes, so needs to be handled with care when setting.
Lab created emeralds were first grown in the 1930's and since then technological advancements has meant that they have become bigger and better. A man-made emerald has the same chemical and physical properties as a natural emerald, yet without the numerous inclusions. Today, lab grown emeralds are becoming an increasingly popular choice.