The unsung heroes of the Gemological Institute of America fluorescence study are people who know nothing about gemology. To determine what fluorescence does to diamonds, GIA called upon not just its trained graders, but also its office staffers, who are no more diamond-savvy than the average layperson. This lack of experience was exactly what GIA wanted. With the office workers as stand-ins for typical consumers, researchers asked them if they noticed a difference between diamonds with strong blue fluorescence and ones without it. Most of them didn’t notice a thing.

Then GIA brought in the experts. After examining dozens of diamonds, the trained gemologists didn’t consistently agree on fluorescence’s impact. (The study tested only blue fluorescence, rather than yellow, which is rarer.) And while some thought fluorescence improved a stone’s color in the table-up position, even that was a subject of disagreement. The study, published in the Winter 1997 issue of Gems & Gemology, concluded that except for rare “overblue” stones, fluorescence has no consistent effect on a diamond’s appearance. The findings go on to poke holes in just about every trade objection to fluorescence, including the widely held belief that it “helps” a color grade (see page 148).

Why worry? So if GIA says fluorescence doesn’t matter, and consumers don’t even notice it, why does the trade still fret about it? There are a number of reasons, but the main one seems to be: Old habits die hard. Even with the GIA study, dealers say that strong blue fluorescence generally knocks 5% to 15% off the price of a high-color stone – and makes it a lot harder to sell. “Some people don’t want a strong blue stone, and they won’t look at it even at 20% less,” says Ben Moller, sales manager of E. Schreiber, a New York diamond manufacturer. But ask dealers why, and they’re stumped. “I have no idea,” says Ron van der Linden of Diamex, a New York diamond dealer.

Twisting logic further, for years strong blue fluorescent stones (known until 1938 as “blue-white”) actually carried a premium. (Lower-color diamonds with fluorescence still do.) But dealers say the bias against fluorescence began during the 1970s investment craze. With stones traded “via paper,” graders worried that “strong blues” were really “overblues,” which led to discounts on high-color fluorescent stones. And since many dealers thought fluorescence improved color appearance, they tended to distrust the grades on those stones.

Then came the Korean debacle. Korea had become a major market for fluorescent stones, but in 1993 a muckraking South Korean TV show told viewers that fluorescent stones were worth a lot less than others. Ever since, high-color fluorescent diamonds have been a hard sell not just in Korea, but throughout Asia.

What happens next? So will the GIA study make a difference? In at least one case, it already has. “I had a customer who was hesitant to buy a fluorescent stone,” says van der Linden. “I showed him the Gems & Gemology issue with the study, and it helped immediately.” But New York diamond dealer and publisher Martin Rapaport argues that the markets have their own logic, and the collective wisdom of the diamond industry has already discounted fluorescence. “Studies like this are important, but I don’t know if they will have a big effect,” he says. “If anyone thinks the GIA is right, why don’t they start buying up all the fluorescent stones? There’s a lot of people who would love to sell them.”

Yet some think the bias has already eased a bit. Joseph Schlussel of the Diamond Registry, a New York diamond brokerage, says that with the Asian market less important, so are concerns about fluorescence. Fluorescence is not as disdained in America as it is in Asia. “We try not to buy fluorescent stones, but it’s not a big deal,” says a buyer for one of the largest U.S. retail chains. “If a diamond looks nice, we don’t care if it’s fluorescent or not,” concurs Anthony Fratto of Anthony Jewelers in Palmyra, N.J.

Some note that, ironically, it’s GIA itself that has kept the fluorescence bias alive, by noting it on its lab reports. But Gem Trade Laboratory CEO Tom Yonelunas says the lab lists fluorescence as an “identifying characteristic,” not a grade. Regardless, many tradespeople figure that if it’s on the report, there must be a reason. “It’s become a marketing tool to say my stone is better than yours,” says dealer Bruce D. Verstandig.

The only practical downside to fluorescent stones is that under disco “black lights” they turn blue, and if a woman’s wearing one, she might panic. Yet even dealers acknowledge this is a slim thread to hang a 5% to 15% discount on. “It doesn’t make a lot of sense to me,” says van der Linden.

What’s ironic is that while dealers tend to shy away from fluorescent stones for business purposes, they have no problem using them as gifts. For example, van der Linden gave his wife a diamond with strong blue fluorescence, and he claims many other dealers have done so as well. “Stones with fluorescence tend to have a fine, crispier material in general,” he says. “I have no problem with it.” And some hope that, eventually, the trade will say the same.