<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}-->Emerald is the green to greenish blue variety of beryl, a mineral species that also includes aquamarine as well as beryls in other colors. Emeralds, like all colored gemstones, are graded using four basic parameters–the four Cs of connoisseur ship: color, clarity, cut and carat weight.