Lead Glass–Filled Rubies by Any Other Name…

Each gemstone-testing lab currently employs its own language to describe lead glass–filled rubies.

American Gemological Labora­tories calls the ­material “composite ruby,” with an additional comment: “This stone represents a composite of natural corundum and glass, also known as Hybrid Ruby. Additional comments—The material is ­heavily treated…vastly ­improving the ­apparent clarity and adding weight. With special care warnings.”

Gemological Institute of America labels the stones “a ­manufactured product.” The report continues: “This item is a ­combination of ruby and glass. The binding material may be unstable to elevated temperatures and ­chemical agents. Special care should be taken when cleaning or repairing ­composite materials.”

Prior to December, the GIA called the material “ruby with glass or ruby/glass composite or natural corundum with glass or natural corundum/glass composite.”

GemResearch Swisslab has dubbed the product “synthetic glass/treated ruby (GRS-type Hybrid Ruby)” with comments that indicate it is heat-treated and filled with a colored foreign solid ­substance (including lead). The lab also notes that “special care is required when handling the stones, also known as composite ruby.”

Gem Certification & ­Assurance Lab calls the stones “composite ruby–lead glass filled. Composed of pieces of corundum bonded together with glass to imitate the appearance of natural ruby. Requires special care. Avoid ­exposure to heat and chemicals.”

EGL USA describes them as “composite rubies that are lead glass-filled with an unstable ­structure requiring special care, particularly when exposed to ­chemicals and high temperatures. EGL USA will not provide ­certification for a ruby that has a substantial amount of lead-glass filling; decisions are made on a case-by-case basis.”