On the disclosure of rubies & fancy sapphires heat-treated by the "new" method

by Ted Themelis, Gemlab Inc

For more than eight months gemmological laboratories and gem trading associations have been trying to resolve issues surrounding the "new" heat treatment process for yellow, orange and similarly appearing sapphires. At this time, the most current issue is how to disclose this treatment to the consumer in such a way that will be scientifically correct and commercially acceptable.

Figure 1 Madagascan sapphires before and after heat treatment with the "OLD" method.

1. Natural, non-treated Madagascan sapphires before heat-treatment.

2. Madagascan sapphires taken from the same lot and heated using by the "old" method. After the treatment there is noticeable general improvement, where pinkish, salmon-pink, and other colors were produced; however, dark purplish, brownish, pale yellow and other "undesired" colors were also produced.

The key parameters selected and used in the nomenclature of disclosure have varied widely and largely have depended on the target sought and the degree of accuracy desired in describing these treated gemstones. Unified guidelines and agreed methodology for defining the nomenclature of labelling these treated gemstones do not exist; while the disclosure of this treatment is subject to various interpretations that serve differing purposes.

The descriptive term bulk-diffusion, that has been proposed to describing those corundums treated by this "new" method, represents a generic term that specifies a type of diffusion treatment that can be applied to most substances, including gemstones. Although this term is scientifically correct, it does not identify the treated gemstone properly; neither is this term commercially acceptable to most gemstone traders.

Figure 2 Madagascan sapphires before and after heat treatment with the "NEW" method.

1. Natural, non-treated Madagascan colourless, pale yellowish, light pinkish sapphires, before heat treatment, taken randomly from the same lot.

2. Natural, non-treated Madagascan colourless, light pinkish and salmon-pink sapphires, before heat treatment, taken randomly from the same lot.

3. Natural, non-treated Madagascan greenish to yellow-greenish chrysoberyl.

4. Natural, non-treated Madagascan, chrysoberyl with significant concentrations of beryllium, that is above the normal level.

5. Madagascan sapphires taken from the same lot and heat-treated under the "new" method. Note the abnormal colour concentrations at the rim and at the centre. One treated sapphire developed a "blue halo" colour patch, while another sapphire turned to blue colour that had an inhomogeneous colour distribution.

6. Madagasdcan yellow-orange, orange and padparadscha coloured sapphires heated-treated under the "new" method.

7. Clusters of Madagascan sapphires of various colour, heated-treated under the "new" method.

8. Cut and polished Madagascan orange sapphires heat treated by the "new" method.

In my opinion the proposed wording enhanced, although commercially acceptable, is does not identify the product adequately. More importantly, it is scientifically incorrect since the entire lattice of the host corundum crystal treated by this "new" heat treatment process is completely re-arranged. This is not a simple "alteration" of the chemistry and structure of the treated corundum.

Please consider this analogy: what is the difference between for a lady who puts on casual make-up to enhance her appearance, and the same lady undergoing major plastic surgery, a face-lift, and/or silicon-injections and the like to achieve the same purpose?

My proposed wording for this new heat treatment is: HEAT-TREATED (with catalyst)^TM. In my opinion, this wording is scientifically correct and (hopefully) commercially acceptable. Here are the reasons for my choice of this descriptive term:

• The wording identifies correctly that it is a heat-treatment process, and the corundum is HEAT-TREATED.

• The wording indicates that a substance was used externally to influence the post-treatment colour of the corundum, that is it was undertaken WITH CATALYST

What, then, is a catalyst? Simply, a catalyst is a substance that accelerates a chemical reaction without itself being affected. In heat-treating these corundums, the mineral chrysoberyl, that contains beryllium, is used as a catalyst in the chemical reactions taken place during the process. But, beryllium is not the direct cause of the induced colour; for beryllium is not a colour-bearing element and therefore it does not produce the colour in the gemstone.

Here is another analogy: In baking bread, yeast is used to accelerate the various enzyme reactions; but yeast does not make the bread. I hope all gem trade associations will correctly understand and properly use this terminology; so those gemstones treated by this "new" heat treatment will be described by terminology that is both scientifically correct and commercially acceptable.

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