AGL is modifying its disclosure terminology used for heated rubies, by exchanging the term “Inorganic (fluxtype)” with “Heating residues”. As well as including the statement “Heating residues are deposited along healed fractures during the heating process.” as an additional description under their comments section of all grading reports.
A contentious topic for more than a decade is the manner or description in which the healing of fissures during the heating process of rubies are handled.. As part of the heating process for rubies, it is common practice to coat the stones in a variety of fluxing agents. As the temperature increases, these fluxing agents melt, partially dissolve the ruby’s surface and facilitate in the healing of fissures, effectively sealing and reducing the appearance of the fissures and improving the general durability of the stone. AGL has traditionally used the following terminology to describe this enhancement: “Clarity: Inorganic (fluxtype)”, with additional terminology that addressed the relative quantity of material that remained (e.g. faint, moderate, etc.).
In actuality, the use of fluxing agents during the heating process results in a combination of features or materials being deposited and remaining along the newly healed fissures. The previously open fissures are replaced by planes consisting of regrown ruby (synthetic), solidified vitreous melt (glass) and voids (empty bubbles). The relative amount of these three parts depends on many factors. To better try and communicate the multiple and complex nature of these remaining biproducts, many labs around the world starting using the term “heating residues” with terms describing the relative quantity (such as: minor residues in fissures).
Prior to heating rubies are coated with fluxing agents.
As temperatures rise during the heating process these fluxing agents melt and enter surface reaching fissures.
As the ruby cools at the end of the heating process, tiny amounts of ruby (corundum) is regrown healing and bonding the fissures. Also remaining confined to the newly healed fissures are solid vitreous melts and tiny voids.
Roughly over the past 10 years, multiple labs have been using the term “heating residues” to describe this combination of regrown ruby, glass and empty bubbles along the healed fissures. As a result, the industry and users of these reports have come to understand the intended meaning of this term and the relative quantification that accompanies it. Meanwhile, the AGL’s use of the term “Clarity enhancement: Inorganic (fluxtype)” has not provided any greater clarity of this issue or understanding to wholesalers, retailers and consumers.
As a result, effective immediately AGL is modifying its disclosure terminology used for heated rubies, by exchanging the term “Inorganic (fluxtype)” with “Heating residues”. As well as including an additional description under the comments section of all Prestige and FastTrack reports, stating: “Heating residues are deposited along healed fractures during the heating process.”
AGL is committed to providing high quality reporting.
Christopher P. Smith, President American Gemological Laboratories LLC
Christopher P. Smith
American Gemological Laboratories
Tel. (212) 704-0727
E-mal: agl@aglgemlab.com
My thanks to Howard Pomerantz for forwarding this info to the Daily Jewel!
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