The New York based lab has teamed up with GemEx Systems Inc. to provide what it calls "Light Performance™" ratings using the Wisconsin company's Brilliancescope. This instrument combines digital photography and computer analysis to assess a diamond's brilliance, fire and scintillation on a scale from low to very high for each.
Put simply, the Brilliancescope™ takes six digital snapshots of a diamond under different lighting angles, then converts their white areas into pixels which count as units of brilliance and its colored areas into pixels which count as units of fire. After adding up these white and colored pixels and comparing them to measurements of top-performing diamonds of the same size and shape, a computer assigns a rating for that particular aspect of performance. Then it calculates scintillation (or sparkle) by analyzing the difference in brilliance between each of the six snapshots.
EGL USA says its new Light Performance section, which is offered in conjunction with its standard diamond grading report, helps consumers to distinguish between diamonds which are identical or similar to one another with regard to color, clarity, carat weight, cut and proportions. Currently, there are no other major gem labs issuing reports with performance ratings - although the American Gem Society introduced cut grades for round brilliant diamonds in 1996.