Four Labs Agree on 'Padparadscha' Terminology

The American Gem Trade Association's Gemological Testing Center, the Gemological Institute of America's Gem Trade Laboratory, the Gübelin Gem Lab, and the SSEF Swiss Gemmological Institute all have agreed that the padparadscha-like orange-on-pink corundum recently encountered in the market is to be called "treated sapphire." Previously, both the AGTA lab and GIA's GTL had called the material "surface diffusion-treated sapphire."

From now on, reports for these treated sapphires will read:

"Species: Natural Corundum

"Variety: Treated (Orange) Sapphire

"Comments/Treatments: Indications of heating.

"The orange coloration of this stone is confined to a surface-related layer."

But in a combined statement, the labs noted that "none of the agreeing laboratories knows of a likely mechanism that could produce these visual effects or apparent differences in trace-element concentrations from the rim of the stone to the interior, other than diffusion of a chemical or chemicals into the surface of the stones.

"Nevertheless," continues the labs' position paper, "as the trade usage of the term 'diffusion' without any qualifier (such as the inadvertent dropping of the word 'surface,' hence 'surface diffusion'—see the CIBJO rules) has, upon analysis, been found lacking both in terms of technical accuracy and descriptive purpose, it has been decided to remove the term from our report wording in relation to this treatment."

According to the labs, "the term 'treated' has been applied before 'sapphire' for sapphires that have been surface treated, so they may be easily separated from those that do not owe their color to a surface-related layer." And in the labs that apply the variety name "padparadscha" to those sapphires that display an orangey pink to pinkish orange face-up appearance, the name "padparadscha" will not be applied to these new treated stones.

"It is vitally important that the report clearly establishes that the orange coloration is confined to a surface-related layer," say the labs. "This is significant for two reasons. First, this new form of orange coloration is distinctly different from the orange color zones that may result in the interior of sapphires subjected to traditional types of heat treatment, as well as from naturally occurring orange color zones that may be encountered in non-heated sapphires. Second, the buyer or owner of the stone must fully understand that if the stone is recut for any reason, the color is likely to change."

Cecilia Gardner, executive director and general counsel for the Jewelers Vigilance Committee, says the new identification wording meets the requirements of the FTC Guidelines. "It is compliant," says Gardner, "but it can be improved."

Gardner also thinks the one-line comment noting that the color is confined to a surface layer "should be explained," since consumers may not understand the implications for special care. "I would suggest adding a phrase to include 'Avoid recutting or repolishing,' " Gardner says.

A future issue of JCK will include a detailed analysis of the labs' decision.