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AGL Will Not Be Classifying New Ruby Treatment As Composite Ruby

American Gemological Laboratories (AGL) has concluded its initial investigations into a new ruby treatment which has been entering the market. Over the past year, another new ruby treatment has been coming out of Thailand and is offering a low-cost alternative to more traditionally heated ruby. "The conundrum for the trade has been how to deal with these new stones and what kinds of disclosures need to be made." indicated Christopher P. Smith, President of AGL.

It is the decision of AGL not to classify this new treatment as Composite Ruby, nor to develop another new classification for disclosure of this treatment as a consideration of several factors (see attached of the full press release and frequently asked questions for details, or visit our website at In the lab's opinion this treatment is more similar to the "glass-filled" rubies that were prevalent during the early to mid 1990's than the more recent Composite Ruby. "At that time, the discussions of glass-filled rubies revolved primarily around rough of Mong Hsu ruby that was being treated, with significant amounts of glass-like heating residues that were remaining." Smith indicated "Today, the material we are discussing is coming mainly from Mozambique, but the issues involved are quite similar."

Initial durability studies were also carried out and these stones were found to have less special care requirements than Composite Ruby. AGL cautions that all gems should be properly cared for however these stones were most similar to the more traditionally heated rubies possessing heating residues when exposed to conditions in a jeweler's workshop or with commercial household products.

"It is our opinion that the wording policy we have put in place for this material provide a practical approach for the industry and labs to address these stones and maintain that adequate disclosures are being made available to consumers." Smith concluded.

Frequently Asked Questions:

Why not call this material Composite Ruby?
Although the extent of this treatment may be significant, there are several fundamental differences between this new treatment and the material AGL classifies as Composite Ruby. Of particular note, the glass infused into the Composite Ruby material contains lead and/or bismuth, as well as other potential elements to raise the refractive index of the glass to that of the host ruby. This makes it quite difficult to ascertain the true extent of the treatment without partially dissolving the glass. With this new treatment, it is readily visible through standard microscopy to determine the true extent of the healing and in-filling that has taken place.
Additionally, the lead-glass of Composite Ruby does not participate in the healing of fissures, and the golden color of the lead-glass further augments the color of a Composite Ruby. Neither of which is the case with this new treatment.
Lastly and perhaps most importantly, Composite Ruby carries with it certain intrinsic special care requirements that must be conveyed to bench jewelers and consumers, in order to make certain that inadvertent damage to these stones does not occur. This new ruby treatment has similar care considerations to that of the more traditionally heated rubies, which bench jewelers and consumers should already be familiar with.

Why not just use the term heating residues?
Heating residues is a term that was developed to represent the compound nature of what happens to the fluxing agents used during a more traditional heating procedure. Upon cooling, fissures are healed and what remains along the traces of these previous open fissures is re-grown corundum (i.e. synthetic), a vitreous melt (glass) and tiny voids (contraction bubbles). It is a combination of these three components that defines heating residues.
In this new treatment, some fissure healing does occur, resulting in the development of heating residues. For those stones where the majority of what is taking place involves the healing of fissures, the traditional disclosure nomenclature addressing the quantity of heating residues will be applied. However in many instances, only minor to moderate fissure healing is observed yet open fissures have been filled with a vitreous or glass-like material. In these instances, this treatment is more similar to the clarity enhancement of an emerald or even diamond, where a material is introduced into open fissures to make them less reflective, thereby reducing their visibility and improving the apparent clarity of the stone. For those stones where a significant extent of what is taking place involves the in-filling of fissures in combination with fissure healing, the disclosure wording will address both heating residues and in-filling, with an expanded description under the comments section, to communicate the dual nature of this particular treatment.


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