AGTA Lab Has New Padparadscha ID

By Gary Roskin, G.G., FGA, Senior Editor -- JCK Online, 3/1/2002 2:00:00 AM

Ken Scarratt, director of the American Gem Trade Association's Gemological Testing Center (AGTA-GTC) says the lab now can determine clearer parameters for the color description of padparadscha sapphires. "We didn't just home in on our own science or opinion," notes Scarratt. "We talked to people in all corners of the world—the Japanese market, the Thai market, the U.S. market, of course—and 99.99% of those we spoke with were very clear that padparadscha required a mixture of orange and pink."

The research project examined every potential padparadscha submitted to the lab, "We measured the color of each stone using the GemSpec spectrophotometer," says Scarratt. "We then formed a 3-D model of theoretical and actual data to see where the various colors fell in the corundum gamut, and then looked to see if they were separable by visual means."

The researchers discovered a distinct group of stones that had a pink-orange component. "They were visually different from ruby, pink sapphire, and orange sapphire," says Scarratt, who notes that this distinction allows the lab "to set color boundaries for padparadscha."

One issue that arose during the study was country of origin. "Some purists felt that the name 'padparadscha' is distinctive for a locality," says Scarratt. "To be a 'pad,' the gem has to have the color plus be from Sri Lanka." But the test results showed that stones with exactly the same color of Sri Lankan padparadschas were available in Madagascar and Tanzania. "Looking at the stone, they had the same color," Scarratt notes.

The laboratory's board of directors agreed that country of origin is not a necessary parameter for identifying padparadscha, which should be a color-only call.

Knowing country of origin is important in terms of value. Richard Hughes, a sapphire expert now working for Pala International, an AGTA member in Fallbrook, Calif., notes that there's a huge difference in price between Ceylonese (Sri Lankan) padparadschas and those from Africa. "Value is really a combination of color, history, lore, and treatments," says Hughes.

And history includes locality. "Untreated Sri Lankan padparadschas command the highest price." Most African stones, including those found in Tunduru (Tanzania) and Madagascar as well as the borderline colors from Umba and Songea (both from Tanzania), are treated, says Hughes.

Hughes says color can be subjective as well. In Sri Lanka, for example, he finds that padparadscha is a subcategory of ruby, because of its predominantly pink color. The name "padparadscha" is Singhalese for "lotus blossom." "The lotus flower is pink in the center and a little orange around the edge," says Hughes.

Padparadschas are commonly pastel in tone and saturation, which leaves the darker-toned and richly saturated African "padparadschas" out of the historical lotus blossom definition. The GTC study revealed a consensus that padparadscha must have both pink and orange combined but found differing views on tonality and saturation. Noting the traditional pastel color, GTC will go "a little darker, a little more saturated—up to a point," Scarratt says.

"At the end of the day," says Hughes, "everyone has their own opinion as to what a padparadscha is."