Feature Gems & Gemology, Winter 1999, Volume 35, No. 4

Classifying Emerald Clarity Enhancement at the GIA Gem Trade Laboratory

One of the greatest concerns with emerald filling is the degree of clarity enhancement such treatment represents. Stones that appear to have excellent clarity with the unaided eye are often revealed to have an extensive network of filled fissures, or some in areas that could be easily damaged. Using the GIA diamond clarity grading system as a framework, the GIA Gem Trade Laboratory has devised a methodology to establish the size, number, and position of filled fissures in an emerald and on this basis to classify the apparent degree of clarity enhancement achieved. Each of more than 500 filled emeralds was classified by experienced gemologists to determine the usefulness and reproducibility of the methodology. Backed by this research, GIA will be offering a new emerald report on which the degree of clarity enhancement detected will be indicated as “minor,” “moderate,” or “significant.”