Professional Jeweler Archive: Can Fancies Be Ideal?

March 2000


Can Fancies Be Ideal?

Round cuts have various standards of quality; now a movement is under way to define standards for fancy cuts

The search is on for information leading to the ultimate – or Ideal – parameters for fancy-cut diamonds. The effort is driven by retailers with customers who’ve learned about standards for round diamond cuts and now seek them for fancies, says Peter Yantzer, director of the American Gem Society Laboratory, Las Vegas, NV.

Some fear the cut grades would make fancy-cut diamonds easily comparable, becoming more of a commodity in consumers’ minds. But the AGS Lab is taking these retailer requests seriously. It first considered applying the standards for round diamonds to fancy cuts. “But we realized this just doesn’t work with a lot of cuts, particularly the new cuts on the market,” he says. As a result, the lab has undertaken a survey of all parts of the trade to determine what constitutes ideal pear, heart, marquise and emerald cuts, among others.

To help prepare for discussions sure to arise this year, here’s a review of what’s known about fancy cuts, a look at one dealer’s “semitechnological” way to grade fancy cuts and a glimpse of what the future may bring.

First Sight

Relying on technology to determine standards suggests beauty is quantifiable and not very subjective. You might disagree, but the first thing most people notice about fancy-cut diamonds is – obviously – shape. And shape involves a basic mathematical formula: the ratio of length to width. Length is the variable, and width is the constant, or 1. For example, a 2:1 ratio in an emerald-cut diamond means the length is twice the width. The Gemological Institute of America, Carlsbad, CA, and other diamond experts have devised normal length-to-width ratios as follows:

Emerald cut
1.50-1 to 1.75-1
Pear cut
1.50-1 to 1.75-1
Marquise cut
1.75-1 to 2.25-1
Oval cut
1.50-1 to 1.75-1
Heart cut
1-1 to 1.25-1

While there is room for individual preferences, deviations from these parameters tend to result in diamonds that are unattractively squat or long.

Symmetry is another consideration with fancy-cut diamonds. Heart shapes should have even lobes; marquise diamonds should have equal wings.

In addition, the culet is often more noticeable through the table in fancy cuts than in rounds, so it should be placed centrally, not off to one side.

Bulging bellies, misshapen corners and super thin girdles are other factors to consider.

The Challenge

Light return is perhaps the most critical factor in judging cut quality in round diamonds. It’s crucial also in fancies, though some say less so than in rounds because they were cut more for shape. Light return occurs in the form of brilliance, dispersion and scintillation, but no scientific studies have been published yet on these factors relating to fancy-cut diamonds.

Technology may soon change this, says David Atlas of D. Atlas & Co., a dealer in Philadelphia, PA. Several entities are working hard to devise a standard lighting system and model to quantify light return, says Atlas. Meanwhile, he relies on his own mathematical formulas to grade cut in fancy diamonds: tables that contain idealized table percentages, crown height, girdle thickness and total depth percentages. Deviations divide Atlas’ model into six classes ranging from fine to below average (to see his charts, go on-line to

Atlas cautions his system is backed by experience, not scientific evidence, but he’s confident the day is near for fancy-cut grading. “Consumers have smartened up and know what questions to ask about brilliance – and not just the quality of the cut,” he says. “I realize people don’t want fancy diamonds commoditized, but things are going that way as people seek out more and more answers.”

Technological Direction

GemEx Systems Inc. is at the forefront of light-return research. The Mequon, WI, company sells the Brilliance Scope,™ which measures brilliance, scintillation and dispersion. The device uses a computerized system to measure six lighting angles in reflected and diffused light. “In the lighting angles we determine what percentage of a diamond returns bright white light and colored light, and how they scintillate. Our machine doesn’t care whether the stone is round or fancy-shaped,” says President Randall Wagner.

Brilliance Scope allows you to compare two diamonds in various lighting modes and conditions. Seeing this comparison can help consumers choose between two diamonds. (For a closer look at how Brilliance Scope works, go on-line to

However, Wagner is skittish about an actual grading system. “It shouldn’t be based on geometry or mathematics because geometry can be misleading, even in rounds,” he says. Beauty should be judged on certain results, he says, including light return.

– by Robert Weldon, G.G.

Determining a cut grade for fancy-cut diamonds may be within reach, despite objections that a grade would commoditize them. Gems are courtesy of Philippe Diamond Corp., New York City.

Copyright © 2001 by Bond Communications