特征 Gems & Gemology, Winter 2011, Vol. 47, No. 4

GIA’S Symmetry Grading Boundaries for Round Brilliant Cut Diamonds


Grade boundary limits are presented for 10 symmetry parameters of the round brilliant cut diamond. Starting in early 2012, these values will be used to support and constrain visual symmetry grading on GIA diamond reports. For manufacturers, the boundaries provide useful predictions of symmetry grades. Other symmetry features of faceted diamonds will continue to be evaluated visually.