Emerald is the bluish green to green variety of beryl, a mineral species that includes aquamarine
The most valued variety of beryl, emerald was once cherished by Spanish conquistadors, Inca kings, Moguls, and pharaohs. Today, fine gems come from South America, Africa and Central Asia.
Color is the most important quality factor for emerald. The most desirable emerald colors are bluish green to pure green, with vivid color saturation and tone that’s not too dark. The most-prized emeralds are highly transparent. Their color is evenly distributed, with no eye-visible color zoning.
Emeralds typically contain inclusions that are visible to the unaided eye. Eye-clean natural emeralds are especially valuable because they’re so rare. Most emeralds are treated with oil, resin, and/or polymers to reduce the appearance of inclusions and surface reaching breaks.
The most popular cut is a square or rectangular step cut called the emerald cut. This cut maximizes the shape and weight of the natural emerald crystal. Well-cut stones maximize the beauty of the emerald’s color to create a bright, lively stone.
Fashioned emeralds come in a wide range of sizes. There are emeralds in museums and private collections that weigh hundreds of carats. At the other extreme are tiny emeralds that weigh fractions of a carat. Quality-for-quality, the price of emerald can rise dramatically as the size increases.