Density: 2.7 to 7.5 / Hardness: 7 to 7.5 / Varieties: Emerald – green, Aquamarine – blue to light blue, Morganite – pink, Heliodore – yellow, Goshenite – colourless.
Hexagonal prism, stocky to elongated, even acicular. The faces of the prism are sometimes vertically striated. Elongated prismatic shapes characterize the green and blue varieties. Pink beryl shows stocky prisms and colourless beryl is perfectly tabular.
Ordinary beryl is generally greyish-white and more or less opaque. The most sought-after gem variety is emerald. Its relatively low refractive index gives it a vitreous lustre.
They are found in silica-rich eruptive rocks, pegmatites, high-temperature hydrothermal veins, metamorphic rocks.
Within emeralds, inclusions can be observed consisting of tiny channels or irregular cavities containing a liquid in which a fragment of halite (salt) sometimes floats. These inclusions form streaks that interfere with light and give the stone an appearance that is sometimes called the “garden of emerald”. These very particular inclusions make it possible to distinguish between natural and synthetic stones.