he International Gemological Institute (IGI), the world’s largest independent gemological laboratory, has added a cut grade to its reports for loose fancy shaped diamonds. In addition to traditional polish and symmetry analysis, the institute will now assess the influence of cut quality on light behavior seen in fancy shapes.
“For many decades Carat, Color and Clarity were the main points of emphasis with consumers,” stated IGI CEO Roland Lorie. “In recent years we have seen increasing attention drawn to Cut, first with rounds and now with fancies. IGI has proactively responded to the growing demand for this assessment, in the interest of better serving buyers and sellers alike.”
Unlike round diamonds, for which light behaviour can be predicted with measurements, cut grades for fancy shapes are practically non-existent among the major institutes due to more underlying complexity. For this reason, IGI designed a four-step system combining proportions requirements with visual assessment, explained in a video at www.igi.org/cut-grading.
“We use proportions ranges to identify candidates for the Excellent grade, but our gemologists are now evaluating light return, in addition to polish and symmetry,” noted IGI Laboratory Director Benoit Scheyvaerts. “Given the wide optical variety of fancy shapes, this is not a dispersion or scintillation analysis. It is a basic assessment of overall light return versus darkness.”
Originally piloted with a small group of clients, IGI will now add the cut grade to fancy shape reports at all 20 laboratories worldwide. That grade will be optional to manufacturers for a six-month period of adjustment. In the interest of industry-wide improvement IGI is providing “Guidelines for Excellent” to all producers, identifying ranges of proportions and other factors the institute’s laboratory locations have historically observed to accompany fancy shaped diamonds with the most positive beauty components.