Cutting for Color: What’s the Real Ideal?

Can the color of a round fancy color diamond be improved by cutting it to Ideal proportions? Most cutters and gemologists say no, because cutting a fancy color diamond to an Ideal increases brightness, thereby diluting body color.

But others say that, in some cases, fancy color diamonds can be cut to Ideal and not only keep their color but also improve their performance.

“Mr. Swiss,” a European businessman who owns an important collection of fancy color diamonds (and who wishes to remain anonymous), recently had a Fancy Vivid Yellow round brilliant recut into an Eightstar Ideal. He believed it was too saturated to lose much color. He was right: The stone is still a Fancy Vivid Yellow diamond, but with far better brilliance and dispersion.

Stephen Hofer, renowned colored diamond expert, says this is the result of what he calls “on-axis reflection”—internal reflections that exit the crown along the viewer’s visual axis. That’s what makes the best Ideal cuts look white.

“This is no different than you holding a flashlight, and me holding a mirror,” he says. “I can see the light going right back to your eye. And if I asked you, ‘What color is the mirror?’ you’d tell me, ‘It’s white!’ As soon as I tilt that mirror—or that facet—the mirror becomes increasingly grayish until the mirror is tilted far enough away and it looks black.”

Well-made stones distribute color evenly, Hofer says. “[They let you] look deeper into the stone. You’re able to really bring out some highlights, what we call high-impact colors. The brain is so attracted to those high-impact colors that you almost forget everything else that’s in the stone.”

Some stones should not be recut to Ideals, Hofer says. “For pale stones [with light to medium tone and saturation], the overall intensity and strength of the color will be reduced a little bit, because the majority of the light is coming back along your visual axis.”

Barry Rogoff G.G., a Los Angeles diamond cutter who specializes in Ideal cuts, agrees. “Cutting a less-saturated stone to Ideal proportions does not increase the face-up color. Actually the opposite is true. A diamond cut with an open table (64+ percent) and a flat pavilion, resulting in a stone that has about a 57.5 percent depth, will more often than not result in the color becoming more enhanced.”

“But here’s the rub,” he adds. “Take a round stone, GIA-certified Fancy Yellow. If you recut the stone to a radiant cut, losing about 20 percent of the weight, the result will lead to a 90 percent chance of the color improving to a Fancy Intense Yellow, maybe even [Fancy] Vivid. [That’s because the] angle of the pavilion and the table size have been manipulated and cut in a manner to maximize and enhance the color of the diamond, particularly the pavilion.”

But Mr. Swiss says never cut a nonround to a round. “Recutting a radiant into a round would be a bad idea,” he stresses.

But, if you’re recutting a round, Hofer says it’s OK to consider an Ideal: “Anytime you have a well-laid-out, highly symmetrical round brilliant cut, you’re going to increase and improve the same color by distributing it evenly throughout the face. Smaller tables and higher crown angles can trap color, which is a good thing.”