GIA Nears Release of Diamond Cut Grading System

February 5, 2004

GIA Nears Release of Diamond Cut Grading System

At a presentation during the Centurion Show in Tucson, AZ, the Gemological Institute of America announced it is growing closer to releasing a new diamond cut grading system, probably later this year or early in 2005. The timing will depend on how soon the Institute can fully prepare the trade, from diamond cutters to retailers, so they understand the new system and can explain it to consumers.

GIA's new system represents 10 years of research that has now proven conclusively there's no one Ideal cut. The research reveals there are many different and sometimes surprising cut proportions that yield beautiful diamonds or cuts that have high optical performance, according to Tom Moses, one of several leading GIA scientists who have been working on the research. Moses spoke before a breakfast gathering of Centurion attendees – a small group of higher-end retailers attending the invitation-only show, which is hosted by leading suppliers.

Centurion attendees' main question after the presentation was how GIA will communicate the new system to consumers, many of whom have been taught the "Ideal cut" parameters. Moses says GIA will work on depicting the system graphically as well as providing simple support materials. The traditional Ideal cut will no doubt fall into GIA's top cut category, he says, and can be explained as one option for obtaining a well-cut diamond. It just won't be the only option. Retailers should tell customers new science has led to a broadened definition of the best cut diamonds, to help them understand why the rules have changed.

Retailers Susan Eisen, owner of Susan Eisen Fine Jewelry of El Paso, TX, and Bev Hori, director of education for Ben Bridge Jewelers, Seattle, WA, spoke at the presentation. They say the new system will help them sell consumers on the idea that many diverse cuts will result in pretty diamonds. It will also make some lower colors and clarities of diamonds more salable, says Eisen. From a diamond manufacturers' perspective, speaker Sheldon Kwiat of Kwiat Inc., New York City, told attendees the greater number of cut combinations will help cutters maximize the yield on their rough and could lead to better prices.

Moses also gave an update on the final parts of the GIA research study, which considered other factors GIA needed to evaluate before devising a comprehensive Diamond Cut Grading System.

The framework of the new system will look first at the face-up appearance of a diamond, as expressed by brightness and fire (both already evaluated in previous published GIA research) as well as scintillation effects. Scintillation effects include : 1. Sparkle, defined as the spots of light in a polished diamond that flash on and off as the diamond, observer or lighting moves.
2. Pattern, defined as the size and arrangement of light and dark areas that result from internal and external reflections.
3. Contrast, defined as the relief of light and dark areas that creates the face-up pattern of a diamond.
Negative scintillation effects include fisheyes, dark centers and dark upper girdles.

The new GIA system will also consider the physical shape of a diamond, including its weight and durability. Diamonds that have total depths, girdle thicknesses or overall weights that cause them to look significantly smaller than their actual carat weights will be judged differently, as will diamonds with proportions at greater risk of damage, such as those with extremely thin girdles. Finally GIA will also consider the finish – or polish and symmetry – of a diamond before making an overall assessment of a diamond's cut.

The new GIA Diamond Cut Grading system will apply only to standard round brilliant diamonds on the D to Z color grading scale from Flawless to I3. Modified rounds, fancy shapes and fancy color diamonds will not be included for now, though they may be at some point in the future, says Moses. GIA is also still refining the exact number of cut grades it will have. The grades will be incorporated on GIA Diamond Grading Reports as well as GIA Diamond Dossiers. GIA will be able to reissue older GIA certificates to include the new cut grade. It has been collecting data on cut for some time on diamonds that go through its lab to make the process easier.

In the course of its human observation tests, GIA also learned that diamond evaluators need a standardized lighting and viewing environment to correctly observe the face-up appearance of a diamond. The Institute collected 70,000 human observations of more than 2,000 diamonds from 350 observers. GIA is working on developing a viewing box that will provide that standard environment, according to Moses.

by Peggy Jo Donahue

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