Debating Cut

March 1999


Debating Cut

Reaction is swift to the first part of GIA's study on fashioning a beautiful diamond

Debate over the best diamond cut, which began when the American Gem Society developed a cut grade, moved into high gear with publication of the first part of a study on the subject by the Gemological Institute of America. Discussion of this and later portions of the study (on scintillation, fire, symmetry and color) will shed light on an often-misunderstood concept and give you scientific reasons to justify diamond prices when consumers raise questions.

Heaps of praise. Loads of heat. It's all in a day's work at the Gemological Institute of America since the venerable institution released the first part of its long-awaited study on what comprises the best diamond cut. This part of the study considered brilliance and focused on a computer-generated virtual diamond (see Professional Jeweler,January 1999, p. 31).

Two camps have formed since the study appeared in the fall issue of Gems & Gemology,GIA's quarterly journal:

  • Camp "A" touts the study's historic imperative – this is the first time anyone took the proportion theories developed by famed cutter Marcel Tolkowsky in 1919 and subjected them to analytical, three-dimensional testing.
  • Camp "B" supports the concept of examining cut but questions some of GIA's findings and motives.

"The study bears out what many in the trade, especially cutters, have known for a long time," says Eli Haas, president of the Diamond Dealers Club of New York City and owner of his own diamond trading company, ENH International Inc. "There are a number of parameters, not just one set, that yield superior brilliance," he says.

The reaction of DDC members to the study has been "overwhelmingly positive," he says. "This should be a shot in the arm for retailers too because it releases them from the artificial straightjacket that only a certain rigid set of parameters is best."

Reaction from the American Gem Society Laboratory in Las Vegas, NV, which issues grades for cut diamonds, was positive too – but more measured. "I found the article on the study insightful and, if anything, it will help our business," says Peter Yantzer, AGS lab director. "Our feeling is that once the study is concluded, GIA will end up with a stone that's close to the AGS Ideal."

He cautions that more scientists will have to review the methodology and findings. "I'm not a scientist so I cannot judge the criteria; I am taking the study at face value," he says. "But I do support his [GIA President William Boyajian's] advice in the introduction warning readers not to draw unequivocal conclusions about the study."

AGS might modify its cut grades if the completed GIA study bears up under scrutiny. "If our diamond standards committee decided the study showed conclusively that changes in parameters yielded as brilliant, dispersive and beautiful a stone, yes, we would have to modify our system," says Yantzer.

Joseph Tenhagen, president and director of Diamond Profile Laboratories, Miami, FL, calls GIA's work a very good initial theoretical study. "The main difference between GIA and Diamond Profile Laboratory [which grades cut, including fancy shapes] is that we do practical work," he says. "We work with real diamonds – not virtual ones – and there are differences. In the real world, for example, perfect symmetry [as in GIA's 3-D virtual diamond] is rare."

Craig Walters, vice president at Diamond Profile Laboratory, adds: "We are thrilled that GIA is broaching the subject and that they've opened the door for discussion."

While most of the industry agrees it's time to look seriously at diamond cut, the GIA study raises concerns among members of Camp "B," largely dealers who are longtime supporters of the Ideal cut and those with their own cut grade system.

The study is beneficial because all tiers of the trade should be concerned about cut quality, says Joe Landau, president of J. Landau Inc., Los Angeles, CA. But the study also widens the range of what can be considered good, which could benefit GIA if it decides to issue cut grades later, he says. "This whole study would never have materialized had the American Gem Society not developed a cut grading system that's accepted by so many jewelers," he says.

Some people say the study raised more questions than it answered. "How many people in this industry are scientists and can really understand this study," asks David Atlas of Atlas & Co., Philadelphia, PA, who was one of GIA's study reviewers. Atlas, who developed the Accredited Gem Appraisers Cut Grade system used by a number of diamond dealers, says the world is hungry for conclusions from the study but that it fell short. "Is the conclusion that we are all doing a pretty good job? How long will it be before we have a conclusion?"

Another critic suggests GIA is back-pedaling on several aspects of diamond cut it once stressed in classes and publications. "This is the first time GIA acknowledges Tolkowsky didn't include girdle thickness percentage or total depth percentage in his original thesis," says Martin Haske, owner of Adamas Gemological Laboratories, Brookline, MA. "In the past, GIA erroneously attributed these concepts to Tolkowsky.

"Besides, the report reads as if GIA never taught a cut-grading system before. Noticeably absent from table 3 [which compares cut grading systems] was GIA's own cut grading system, which ranks diamonds into Classes I, II, III and IV, taught in their courses since the 1990s."

– by Robert Weldon, G.G.

Copyright © 1999 by Bond Communications.


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