Diffusion or not, the labs agree but others object

The AGTA’s Gemological Testing Center, the GIA’s Gem Trade Laboratory, the Gübelin Gem Lab, and the SSEF Swiss Gemmological Institute have all agreed that the padparadscha-appearing orange-on-pink corundum recently encountered in the market is to be called simply “treated sapphire”-not diffusion treated, and not surface-diffusion treated.

This is a huge step backwards from what the AGTA lab has already been calling these stones, and in considerable conflict with what GIA itself presented in their laboratory update seminar in Tucson. Both laboratories had called the material, unequivocally, “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.

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.” So the labs do agree that it is a surface-diffusion treatment.

“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.”

What this means, in essence, is that because three of the four labs have not been calling the old surface-diffusion treatment “surface diffusion treated,” all four labs will completely toss out the word “diffusion.” Many in the gemological community are not happy with the new term.

Pala International’s Richard Hughes, sapphire expert and author of the best selling book Ruby & Sapphire, is extremely disappointed with the new identification call. It was Pala’s Web site, Palagems.com, which along with the AGTA GTC’s Ken Scarratt first alerted the trade regarding these stones. Pala also provided the GIA Gem Trade lab with its first samples of these surface diffusion-treated sapphires.

“They’re throwing the baby out with the bath water,” says Hughes. “As I wrote in my book in 1997, `surface diffusion-treated corundum’ is the trade-accepted way to address these stones. If you want to describe them more scientifically, as I also wrote in my book, you can call them `bulk diffusion-treated.’ But don’t throw out the word `diffusion. That is madness.'”

According to lab representatives, however, this is really just the tip of the iceberg. It’s much more complex than what’s related in the press release. They say there are at least two important things at work here:

First, all of the laboratories have agreed to share research and determine a standard identification. This, according to the major players, is for the jewelry industry to see consistency in the trade on the identification of this particular treatment. Historically, such a union of the labs has never occurred.

Second, the laboratories are in a quandary over what to call this new treatment. They all agree that the term “diffusion-treated” has been used incorrectly for years, and to use it now-even with the addition of the word “surface”-would only compound the error, since they feel the process might go further than just the surface layer. It’s an advanced enhancement process that needs more research.

There has always been talk of standardization and cooperation amongst laboratories, but we have never seen anything quite like this before. Four laboratories, all prestigious in their own right, have come together to issue a combined statement and an agreed-upon identification nomenclature. And most incredibly (for even one lab, let alone four), they’ve done it quickly.

Chris Smith, director of the Gübelin lab, and Ken Scarratt, director of the AGTA lab, both mentioned that the labs are proud of the level of cooperation this group-of-four has shown, and hope that the industry takes note of this unique event.

So, what is it? However, what some people in the trade have noticed is that the word-play and omission of the “D” word is tantamount to hiding the truth about the gem’s treatment. According to Hughes, “If this is the result of lab cooperation, then perhaps we ought to return to our old selfish ways. According to AGTA’s own guidelines: `When a seller offers to the buying public a gemstone which has been enhanced, the seller must inform the buyer of the specific enhancement method employed. Plain language must be used; codes and abbreviations are not sufficient.’

“By this definition,” Hughes added, “the proposed wording goes against the AGTA guidelines in that it does not inform the buyer of the specific method of enhancement. And as we all know, lab reports are a major tool used by retailers to sell to the general public. These revised reports are truly negligent in this area.”

Although the treatment looks like “surface diffusion” to most trained gemologists, say the labs, there are a couple of problems-big problems-with calling these stones “diffusion-treated.” First and foremost is the actual definition of “diffusion.” Scientists familiar with gemology have been calling attention for years to the misuse of the word “diffusion” alone, but have had little success in catching anyone’s ear.

To gemologists, the words “surface diffusion-treated” means the introduction of a coloring agent, by heat treatment, into the surface of a gemstone-e.g., titanium into colorless sapphire to make it blue, or as with these new stones, the introduction of beryllium to make them orange. What some gemologists don’t know, however, is that “diffusion” alone simply means the movement of ions or atoms, by heat treatment, within the stone. This means that all heat-treated sapphires-and that’s most every sapphire these days-are, in effect, diffusion treated. Thus, labs should properly use the term “surface diffusion,” rather than just “diffusion,” when describing this outside-in movement of coloring agents.

According to the four labs, so far only three stones have been thoroughly tested to find this unusual amount of beryllium. More testing should be done; in fact, representatives of the labs are right now gathering in Bangkok to purchase, test, and study more of these stones. But even with the small amount information that has been uncovered, the labs feel that it might be possible to diffuse color throughout the entire gem. This would make it almost impossible for the lab to quickly identify such a stone, and it would certainly be confusing to use the term “surface diffusion-treated sapphire” for this type of stone.

The remainder of this story will appear in the May issue of JCK magazine.