“In light of new developments, we have reconsidered our terminology used for ruby treatments,” says Dr. Henry Hänni, director of the SSEF Swiss Gemmological Institute in Basel. Because ruby enhancement combines three elements—transforming color, increasing transparency, and healing fissures (or filling larger cavities)—SSEF has modified its ruby enhancement terminology, saying that judging only the presence of foreign residues neither reflects nor directly relates to the total improvement achieved.

“Ruby treatment is a complex process, where heat, together with flux-like substances, acts in different ways to enhance the treated stones,” says Hänni. “Heat alone may change the color and transparency of the ruby.” He notes that the addition of flux-like materials, along with heat, leads in most cases to an artificial healing of fissures that can leave glassy residues in fissures or fillings in larger cavities. “What we can see with magnification is usually the presence and amount of these glassy residues,” Hänni says, adding that it’s not possible to determine how much the color changed or how much the transparency changed, but only how many fissures were originally present in the ruby.

The lab’s former qualification, “Extent of Enhancement,” did not reflect all the possibilities. The total enhancement is not related to the visible traces of glass, says Hänni. So instead of stating the degree of enhancement, SSEF now confirms the “Amount of Residues.” The new statement of disclosure uses the same terminology to indicate the amount of trapped flux—minor, moderate, or significant.

“The comment ‘with indications of thermal enhancement’ stays unchanged for heated stones with recognizable thermal treatment,” Hänni says.

A general statement on the extent of enhancement—including color improvement, transparency improvement, and fissure healing—is not feasible, says Hänni. “An indication of a heat treatment and a gradual disclosing of glassy residues found is, at this point, the best practical formula to express what a dealer needs to qualify a heated ruby.”