: Look for "vivid" saturation; desaturated stones can look gray or brown.
Emeralds are almost always treated to improve their appearance. Beginner's Guide to Buying an Emerald Gemstone
: Nearly all emeralds contain natural inclusions, often called a jardin (French for "garden").
: The most desirable emeralds have a medium to medium-dark tone. If the tone is too light, the stone is considered green beryl.