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.”