Professional Jeweler Archive: GIA Nears Release of Diamond-Cut Grading System

April 2004

Diamonds/Gemology


GIA Nears Release of Diamond-Cut Grading System

Institute will educate jewelers about the new standards


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

GIA’s new system is backed by 10 years of research proving conclusively there’s no one ideal Ideal cut. The research reveals many, and sometimes surprising, cut proportions yield beautiful diamonds or high optical performance, says Tom Moses, one of several GIA scientists who worked on the research.

Communicating with Customers

The main questions of retailers who attended the announcement during the Centurion Show relate to 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 and providing simple support material. 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 one. To help explain the change to customers, retailers should say new science has led to a broadened definition of the best-cut diamonds.

Retailers Susan Eisen, president of Susan Eisen Fine Jewelry in 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 many cuts will result in pretty diamonds. It also will 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 rough and could lead to better prices.

Scintillation and Physical Factors

Moses gave an update on the final parts of the GIA study, which also considered other factors GIA needed to evaluate before devising a comprehensive cut grading system.

The new system will look at brightness and fire (already evaluated in GIA research), as well as scintillation effects. Scintillation effects include:

1. Sparkle: The spots of light in a polished diamond that flash as the diamond, observer or lighting moves.

2. Pattern: The size and arrangement of light and dark areas resulting from internal and external reflections.

3. Contrast: The relief of light and dark areas that creates the face-up pattern of a diamond.

Negative scintillation includes fish-eyes, dark centers and dark upper girdles.
The new system also will consider the physical shape of a diamond, including its weight and durability. Diamonds with total depths, girdle thicknesses or 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. GIA also will consider the finish – the polish and symmetry – of a diamond before making an overall assessment of a diamond’s cut.

Which Diamonds Get the Grade?

The new GIA Diamond-Cut Grading system will apply only to standard round brilliant diamonds on the D to Z color scale from flawless to I3. Modified rounds, fancy shapes and fancy color diamonds will not be included for now, though they may be in the future, says Moses.

GIA is still refining the number of cut grades it will have. The grades will be incorporated on GIA Diamond Grading Reports and GIA Diamond Dossiers. GIA will be able to reissue older GIA certificates to include the new cut grade. It has been collecting information 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 diamond evaluators need a standardized lighting and viewing environment to correctly observe the face-up appearance of a diamond. GIA collected 70,000 human observations of more than 2,000 diamonds from 350 observers. GIA is developing a viewing box that will provide that standard environment, says Moses.

– by Peggy Jo Donahue

These diamond illustrations and photo are from GIA’s first cut study. From the top, a computer generated profile, a virtual diamond and a real diamond with comparable proportions. The study used computers and human observations to reach its conclusion that many different cut proportions yield beautiful diamonds.

Top two illustrations and bottom photo by Vincent Cracco are courtesy of GIA.

Copyright © 2004 by Bond Communications