The American Gem Trade Association and the International Colored Stone Association have agreed to make the following declaration in regard to the new treatment of corundum that originated in Thailand. “Given the continued use of this process and the resulting confusion as to its disclosure,” said a statement from the two groups, “our Associations have found it is necessary to provide absolute clarity regarding its description. We recommend this process be called a bulk diffusion process.

“This process involves the addition of foreign elements at temperatures well above those used in the traditional heating process to create and/or induce the color alteration. Depending on the depth of the color alteration, the color may be removed by repolishing or chipping of the stone.

“The accurate disclosure of this process is of vital importance to ensure the integrity of our industry and for the protection of the consumer. Our Associations have approved the descriptions listed below in accordance with our respective disclosure methodologies.

“The following is the industry-endorsed disclosure code, which applies to commerce in the United States and is required of AGTA members.

“AGTA: Bulk Diffusion Process

“Disclosure code (as per the Gemstone Information Manual): U

“Please note that the current GIM does not make reference to the “bulk diffusion process,” only “diffusion.” The GIM is currently being revised to include this more current definition.

“It is a violation of the FTC Guides to fail to disclose the bulk diffusion of gemstones in advertising, promotional literature, or commercial documents. If the color of the bulk-diffused gemstone does not permeate the entire stone, then the following statement must also appear:

“Although the color induced in bulk-diffusion-treated gemstones is permanent under normal conditions, if it does not permeate the entire gemstone, recutting or repolishing is not recommended.

“The above disclosure language must be printed in a type size and location so as to be conspicuous.

“The following is the code for disclosure which is required of ICA members and is used in commerce internationally.

“ICA: Treated Stone

“Disclosure code: T

“The ‘T’ category includes all gemstones that require explicit process disclosure. An example of this disclosure would be: ‘The color in this sapphire has been achieved through a process which includes the addition of foreign elements to achieve the desired color alteration. This treatment is a diffusion process and the coloration may be confined only to the surface or in some cases throughout the gemstone. Recutting may result in a change of color.’ “