The IGI system maintains the highest possible level of accuracy in describing the Proportion or Cut Grade, while at the same time, avoids complex and sophisticated concepts. Their goal has always been to follow a viable system that respects the mathematical laws of light reflection and refraction for polished diamonds. It observes the proportions and dimensions, but in combination and harmony with the quality of polish and symmetry. It is transparent and easily predictive for manufacturers as well as traders and is also understood by all levels of the industry, including the retailers and the consumer.
All of this has led IGI to keep the more traditional and more transparent concept of describing Cut Grade on round brilliants. Although �traditional� in concept, the existing IGI Proportion Chart has been slightly adjusted recently in order to take into account current trends and market realities. The IGI Grading Reports have been slightly re-formatted and will now also include Crown angle (in addition to Crown height), Pavilion angle (in addition to Pavilion depth) as well as total depth. The grade �Proportions� will be replaced by �Cut Grade.� The newly formatted reports will be available as of June 1, 2006.
The highest Proportion Grade initially started with �Very Good� followed by �Good,� �Fair� and �Poor.� In 1995, we introduced �Excellent� as the highest grade and in 1996 the IGI Hearts & Arrows Diamond Report was created. Proportion grading is not new at IGI or at the majority of European or Japanese laboratories. Since the late 1970�s, reports for round brilliants produced from Europe to Asia had descriptions of Proportions or Cut.
The debate on Cut Grading started in the US during the 1990�s. Surprisingly, none of the American gemological laboratories were grading overall Cut for polished diamonds until then. At IGI we have been monitoring a large number of cut-related discussions as well as closely analyzing extensive research (carried out in the US and Russia) and felt it would be appropriate to remind our colleagues and clients the Proportion or Cut Grade has a much older history than most people know.
Hearts & Arrows:In fact, Hearts & Arrows (H&A) are more then just a visual effect that appears when observing such a diamond through a specially designed scope; H&A are extremely difficult to polish; the tolerance for proportions and angles is so narrow that it virtually turns H&A into the most uniformly cut brilliant available on the market.
We therefore quickly understood the value proposition associated with H&A. More than just an optical effect, it is a user-friendly method for verifying and confirming highest levels of facet symmetry and most uniform proportions. Today, many manufacturers are still trying to correctly polish H&A, often in vain. The IGI H&A reports show photographs and/or illustrations of the H&A pattern.