Unified AGTA / GIA / Gübelin / SSEF disclosure policy
For the new corundum treatment coming out of Thailand

The AGTA Gemological Testing Center, the GIA Gem Trade Laboratory, the Gübelin Gem Lab, and the SSEF Swiss Gemmological Institute have agreed report wording that will be applied to those sapphires that have recently entered the market and have been treated to produce an orange color component sometimes resulting in an appearance close to that of padparadscha.

Figure 1 This diagram illustrates the appearance of this shallow surface related coloration, when the stone is immersed in methylene iodide, over a diffused light source.

Introduction
Over the past approximately six months, significant numbers of pinkish-orange to orangy-pink sapphires have been entering the international gemstone market. The increased availability of this color variety of corundum is the result of a new treatment taking place in Thailand, which is being applied to certain colors and sources of corundum (e.g. pink sapphires from Madagascar and brownish-red rubies from Songea, Tanzania).

These stones are being treated at high temperatures to produce a surface related orange coloration. In different samples that have been treated in this manner, the surface related coloration was usually restricted to a shallow layer, however, this layer may also extend to a greater depth. The induced orange layer combines with the original color of the stone to produce the overall color appearance after treatment ( shallow color layers produce an orangy modifier to the original color, whereas deeper color layers produce a more dominant orange appearance).

Figure 2 These two photos are of the same stone. Clearly visible in both viewing directions is the shallow, surface related orange coloration that was induced as a result of this new treatment.

The surface related orange coloration of these stones is reminiscent of the shallow coloration that is characteristic of the blue and red surface diffusion treated corundum. However, certain features are different. The depth of penetration of this orange color layer may be significantly deeper than what is seen with blue and red surface diffusion treated corundum. As a result, the outlining of facet junctions which clearly identifies those types of treated corundum is not observed in this new type of treatment. In addition, routine chemical analyses do not readily identify an elevated concentration of typically encountered color-causing elements (such as titanium or chromium), although highly advanced analytical testing has produced indications that much smaller amounts of lighter elements (such as beryllium) may be responsible for the induced orange coloration.

As a result, extensive debates have been taking place throughout the gemstone trade and between gemological laboratories, as to how to describe or disclose this new type of treatment. It became evident that a unified disclosure policy to address this case was urgently needed to help settle the current atmosphere of uncertainty and permit the proper disclosure of this treatment. Therefore, during the Tucson Gem and Mineral Show, the directors of the AGTA-GTC, GIA-GTL, Gübelin and SSEF laboratories came together to formulate a unified terminology and disclosure policy. This event marks the first time in our trade that four major, international gemological laboratories have come together and produced a successful and timely solution to address a problem that was facing the colored stone industry.

Unified Declaration Policy
This unified terminology and disclosure policy applies only to those color varieties of corundum that reveal evidence of heat treatment and possess a surface related orange color layer, as described above. There are two parts to the agreed upon declaration policy. The first concerns the use of the name "padparadscha" and the second concerns the actual wording indicated on the laboratory report.

1. For the labs that apply the variety name padparadscha to those sapphires that display an orangy-pink to pinkish-orange face-up appearance: The name "padparadscha" will not be applied to these newly treated stones.
2. On all reports the following statements will be made:
   
   

   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.

POSSIBLE QUESTIONS AND ANSWERS

Why not Padparadscha?
We believe that this new treatment has been applied to imitate a "padparadscha-like" color appearance, but because the orange color component is confined to a surface related layer, they should not be identified by the color variety Padparadscha.

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

Why the term "Treated Sapphire"?
The term "treated" has been applied before "sapphire" for sapphires that have been surface treated, so that they may be easily separated from those that do not owe their color to a surface related layer.

Why not the term "Diffusion-Treated"?
None of the agreeing laboratories know of any other likely mechanism that could produce these visual effects or apparent trace element concentrations, other than diffusion of a chemical or chemicals into the surface. As the trade usage of the term "diffusion" without any qualifier (such as the inadvertent dropping 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.

Does the penetration depth of the orange color alter the report wording?
No, if any amount of pink is seen to be present under the overlying orange, the same report wording applies.

In terms of the ICA "NET" system, where do these new treated sapphires fall?
They fall in the T category.

Will all heated orange / pink stones be reported in this manner?
No, those stones that have been subjected to traditional heating will be disclosed according to the traditional/standard policies of each lab. Those stones will not have the word "treated" in their description, nor will they be subjected to the additional comment.