Emerald is a gemstone and a variety of the mineral beryl (Be3Al2(SiO3)6) colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5–8 on the Mohs scale.
A fine emerald must possess not only a pure verdant green hue as described below, but also a high degree of transparency to be considered a top gem.
In the 1960s, the American jewelry industry changed the definition of "emerald" to include the green vanadium-bearing beryl as emerald. As a result, vanadium emeralds purchased as emeralds in the United States are not recognized as such in the UK and Europe
PRIMARY GEMSTONE: Natural Emerald in a medium to dark green color variety of Beryl Specie Being from the Beryl Specie the basic chemical composition is Silicate of Beryllium a Aluminium Natural Emeralds are green in color because of the presence of Beryllium and vanadium Natural Emerald has a hardness of ‘7.5’ to ‘8’ on the Moh’s scale of hardness. The other physical properties of natural Emerald includes a refractive Index of ‘1.575-1.590 and moderate specific gravity of ‘2.70+’.