Beryls are popular gems, not only on account of their magnificent colours. Their appeal also lies in their high brilliance and qualities such as their hardness (7.5 to 8), which makes them admirably well suited for use in jewellery.

Beryl also occurs in mica schists of metamorphic-hydrothermal deposits wherein the schists and other associated host rocks form by chemical interaction between granitic rocks or pegmatites and enclosing basic (silica-deficient) rocks. The chemical ingredients necessary for the formation of the beryl frequently migrate from the granitic material into the adjoining basic rocks where the beryl crystallizes, changing the original basic rock composition through the process known as exometamorphism. If the basic rocks contain the element chromium, small amounts of the chromium may be incorporated into the beryl structure thereby giving the intense green color characteristic of the gem beryl variety emerald. Most emerald deposits are of this type with emerald occurring in a schist matrix, although some of the world's most famous emerald deposits are of hydrothermal origin where heated mineral bearing liquids or gases from deep igneous sources later cooled and crystallized along rock fractures.