The International Gemological Institute (IGI) has introduced Light Performance Grading Reports, which feature round brilliant-cut diamonds with remarkable optical properties. The IGI Light Performance grading system assigns values to each diamond to offer a primary score reflecting the overall strength of light performance, as well as sub-component scores for brightness, fire, and contrast.
The IGI system defines “brightness” as all reflected and refracted white light. “Fire” refers to diffused light that appears as flashes of colour. “Contrast” refers to the balance and intensity of light and dark areas at typical viewing distances. The major “Light Performance” score reveals the overall strength of brightness, fire, and contrast as they combine to produce scintillation, which many consider to be a diamond’s most striking feature.
“Light performance is directly connected to a diamond’s appeal,” claimed IGI CEO Tehmasp Printer. “In recent years, there has been an increased interest in broader performance analysis. IGI responded by developing an easy-to-understand, science-based light performance report as well as cutting instructions for diamond producers, enabling them to get the best outcomes. We are delighted to provide manufacturers, sellers, and purchasers of high-performance diamonds with thorough information on these popular facets of diamond beauty.”
IGI researchers created the method by combining ray-tracing software with slope proportions logic to evaluate a wide range of parametric data sets for round-brilliant cuts across 18 table sizes. Parameters determined to be of excellent performance were further evaluated utilizing structured light environment visualizations and physical science to create scores for generally cited aspects of diamond beauty.
The scores are supplemented by a computer-generated map of the diamond in an instrument called ‘Ideal-Scope;’ a structured light environment that reveals overall light return, light leakage, and contrast. That image corresponds to the diamond’s actual parametric data, allowing for further expert investigation of fundamental light behaviour.