Professional gem laboratory certification is available to identify and document the exact characteristics of an emerald. The United States and Switzerland are home to the most renowned and respected independent gemstone laboratories. These laboratories include: Gemological Institute of America (GIA), American Gemological Laboratory (AGL), Gem Research Gübelin Gem Lab, Swiss Gemological Institute, C. Dunaigre (CD) and Gem Tech Laboratory (GGTL).
Because this process is quite expensive, most emeralds that are certified are fine quality and weigh 3 carats and up.
Due to their unique composition, emeralds require special testing equipment – more costly than those for diamonds – in order to properly identify the type, origin, and enhancement level. Enhancement levels are classified as: None (No-oil), Insignificant, Minor, Moderate, Strong and Prominent. None being the rarest and prominent being the most prevalent.