The International Gemological Institute (IGI) has added a cut grade to its reports for loose fancy-shaped diamonds that will assess the influence of cut quality on light behavior.
IGI will offer the new category to manufacturers as an optional feature for the first six months, it said last week. The lab originally piloted the fancy-shape cut grade, which will be implemented at all 20 of its global facilities, with a small group of its clients.
“For many decades carat, color and clarity were the main points of emphasis with consumers,” noted 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.”
While light behavior for round diamonds can be predicted with measurements, cut grade for fancy shapes has been virtually nonexistent due to its greater complexity, IGI explained. To counteract this, IGI designed a four-step system combining proportion requirements with visual assessment.
“We use proportion ranges to identify candidates for the excellent grade, but our gemologists are now evaluating light return in addition to polish and symmetry,” added IGI lab 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 the overall light return versus darkness.”
BRON: Rapaport 4-9-2022