Grading Fluorescent Diamonds in a New Light?

By Gary Roskin, G.G., FGA -- JCK Online, 2/1/2008 2:00:00 AM

When the Accredited Gemologists Association hosts its annual conference in Tucson, Ariz., on Feb. 6, one of the most controversial questions in diamond grading will be on the agenda: How do you accurately grade color in diamonds that fluoresce blue under ultraviolet light?

Standard grading lights give off a small component of UV light that causes fluorescent diamonds to glow blue. The blue fluorescence can enhance the diamond's inherent body color, creating what some call a “perceived” color. Since that gives the diamonds an advantage over stones that don't fluoresce, some suggest using lighting with no UV content.

According to gemologist-author Antoinette Matlins, who will chair the conference, lighting units that totally eliminate UV light may be available soon. New lamps could provide lighting to grade inherent body color (void of UV) and also the perceived color resulting from the presence of UV fluorescence.

Matlins says that while the trade would resist new color-grading nomenclature, benefits could outweigh shortcomings. She notes that positive comments on fluorescence might reduce “the prejudice that now pervades the marketplace against fluorescent diamonds.”

Serving on the panel of experts for this year's event are Sheldon Kwiat, president, Kwiat Inc.; Stanley Hogrebe, chairman, Dazor Lighting; Tom Tashey, chief executive officer, Professional Gem Sciences; Peter Yantzer, executive director, AGS Laboratories; Jack Ogden, CEO, Gemmological Association of Great Britain (Gem-A); and Ron Geurts, research and development manager, GIA Belgium. Gary Roskin, JCK's gemstone editor, will moderate.

For more information on the AGA conference, call (619) 501-5444 or visit www.accreditedgemologists.org.