IGI is pleased to announce the debut of the new Light Performance Dossier, a streamlined version of the IGI Light Performance Report, expanding the reach of its groundbreaking diamond light performance system. This innovative dossier, available for qualifying round brilliant diamonds graded by IGI or elsewhere, extends the lab’s science-backed, repeatable system to any diamond with exceptional performance. This service is intended to benefit both the industry and consumer buyers by providing a wide-ranging, consistent standard for assessing and clearly communicating the most popular beauty components of a diamond’s performance.
60 second video, followed by useful links
Come see demos and samples @ JCK, Booth #14055
- Attend “Leveraging Light Performance to Grow Your Business”
- Live at IGI’s booth daily at 11:30 am and 4:30 pm
- Check out the onsite lab and same-day grading for diamonds and jewelry
- Receive a free 10X Loupe when you sign up for the IGI GemBlog (email required, while supplies last)
Book a 30 minute meeting now
Contact IGI directly
- IGI New York: newyork@igi.org
- IGI Los Angeles: losangeles@igi.org
- Contact IGI at any worldwide location
IGI Light Performance Reports
The round brilliant light performance system was developed by IGI researchers who made over 66,000 separate analyses using ray-tracing software and slope logic to assess the light performance of round brilliant proportions sets spanning 18 table sizes. Parameters judged to have Exceptional performance, overall, were isolated and further assessed using structured light environment renderings, slope logic and physical science to calculate repeatable scientific values for the resulting optical properties.
What sets this system apart is a unique focus on normal viewing distances. After polling observers, IGI concluded that the most common distance for viewing light performance is approximately 40cm. This is the distance from which the contrast component is judged. IGI also made assessments at 25cm and 20cm, applying deductions for obstructed patterns at those distances to the Contrast score (not the light performance score), since the observed deficits do not negatively impact light performance at more common viewing distances.
Components
The IGI Light Performance Report provides the following scores for diamonds in the Exceptional range.*
- Light Performance: The overall strength of light return (versus leakage).
- Brightness: All reflected and refracted white light
- Fire: Dispersed light seen as flashes of color
- Contrast: Balance and intensity of bright and dark areas
The Ideal-Scope Representation, generated with ray-tracing software, conforms to the diamond’s specific parametric averages, permitting further verification and analysis of its fundamental light behavior in the Ideal-Scope, a scientific light performance assessment tool.
*Note that light performance analysis is based on external proportions and does not account for dense clarity characteristics/reduced transparency. See the IGI LP Grading Manual for exclusions.
IGI Light Performance Cutting Guidelines
IGI provides these guidelines as a free resource to diamond producers seeking to improve or
optimize the optical properties of round brilliant diamonds with average crown angles between
30.0 and 39.5 degrees, average pavilion angles between 40.0 and 42.0 degrees, and table sizes
between 50 and 65 percent.
These guidelines apply to round brilliant diamonds in common weights with no culet, medium
girdle, 50% average star length and 78% average lower girdle facet length. Light Performance
and Contrast scores may be reduced when average lower girdle facet length is below 76%.
