IGI Launches New Light Performance Reports for Round Brilliant Diamonds

The International Gemological Institute (IGI), has introduced Light Performance Grading Reports showcasing round brilliant cut diamonds with exceptional optical qualities. The IGI Light Performance grading system calculates values for each diamond to provide a primary score, indicating the overall strength of Light Performance, along with sub-component scores for Brightness, Fire, and Contrast.

Diamonds of the same shape can exhibit different visual characteristics. IGI’s new light performance assessment supplements traditional diamond grading by communicating the unique aesthetic story each diamond tells, with scientific analysis which explains its appeal.

In the IGI system: “Brightness” refers to all reflected and refracted white light. “Fire” is dispersed light seen as flashes of color. “Contrast” is the balance and intensity of light and dark areas at common viewing distances. The primary “Light Performance” score indicates the overall strength of brightness, fire, and contrast as they combine to produce scintillation; considered by many to be a diamond’s most appealing quality.

“Light performance is directly connected to a diamond’s appeal,” stated IGI CEO Tehmasp Printer. “In recent years we have seen increasing interest in expanded performance analysis. IGI has responded by creating an easy to understand, science-based light performance report along with cutting guidelines for diamond producers, empowering them to target the best results. We are pleased to support manufacturers, sellers, and buyers of high performing diamonds with detailed information on these popular aspects of diamond beauty.”

IGI Light Performance Grading Methodology

The system was developed by IGI researchers using ray-tracing software and slope proportions logic to assess a wide range of parametric data sets for round-brilliant cuts spanning 18 table sizes. Parameters judged to have exceptional performance were further assessed using structured light environment renderings and physical science to calculate scores for commonly described aspects of diamond beauty.

The scores are supported with a computer-generated map of the diamond in an instrument called ‘Ideal-Scope;’ a structured light environment which reveals overall light return, light leakage, and contrast. That image conforms to the diamond’s actual parametric measurements, permitting further expert analysis of fundamental light behavior.