Step 2: Advanced Gemology

Lesson 13

Ruby-Glass Composites or Leaded Glass Treated Rubies?

During a meeting of the Laboratory Manual Harmonization Committee (LMHC) in 2007, Dr. Pornsawat Wathanakul (Scientific Advisor to the GIT member) reopened discussions on glass fracture filling in ruby. Several members had noted myriads of large gas bubbles within the newer material submitted to their laboratories. In many cases, they found the glass filled wide seams crossing facets and accounted for an ever-increasing volume of the finished product. Furthermore, members surmised from observation that the glass held the material together. In other words, the glass acted like an adhesive.

Following discussions, the LMHC agreed this treatment went beyond any “fracture filling or clarity enhancement” process. The group decided to describe this (heavily treated) material as “ruby-glass composite” on all future identification reports.

Ruby Vocabulary Revisions

The Jewelers Vigilance Committee (JVC), along with other trade organizations, submitted a brief to the Federal Trade Commission (FTC). They suggested a number of vocabulary revisions to its Guides to ensure a standard throughout the industry, such as the following:

  • “Natural” should refer to untreated rubies.
  • “Treated” should identify rubies treated with traditional methods, such as heating to modify