In the past, the only means of determining the diamond’s symmetry grade would have been the judgment and experience of the grader. Quantifying these features by instrumental measurement like scan from Helium Polish provides a more consistent basis for symmetry grading, and gives cutters the details needed to improve their diamonds’ symmetry.

GIA recently introduced boundary limits for 10 symmetry parameters for the Round Brilliant Cut diamond. These values will be used to support and constrain visual symmetry grading on GIA diamond reports from early 2012. Additional measurable parameters, aspects arising from combinations of these parameters, and facet related symmetry variations will continue to be assessed visually.

Reports