A precious gemstone formed from the mineral beryl, with a deep green hue

created by trace elements of chromium. Emeralds are graded along the same 4Cs
as diamonds, with the most important being c, divided into hue, saturation and
tone. To be classified as an emeralds, rather then a green beryl, the tone must be
medium to dark. Emeralds are often highly included, so are graded by eye, rather
than used a 10X loupe, as per diamonds. An eye-clear emerald is considered