em·er·ald | ˈem-rəld
A gemstone of the beryl family
An emerald is a gemstone in the beryl family. It gets its green coloring from a trace amount of chromium and sometimes vanadium and has a hardness of 7.5-8 on the Mohs scale. Because most emeralds are included, they are generally considered poor in terms of toughness and are relatively easy to break. Emeralds are graded using the four parameters of most gemstones - color, clarity, cut, and carat weight. While color remains the predominant measurement for the quality of the emerald, clarity is nearly as important due to the unique nature of the gem. Vanadium emeralds are not labeled as such in the UK and Europe, as the newer variant is referred to as the “Colombian emerald” in the US.