A lab-grown ruby was found to have been subjected to a treatment usually reserved only for natural stones.
The GIA lab in Carlsbad, California, USA, received the gem for grading and staff were surprised to find that fractures had been filled with lead glass to minimize their appearance and enhance overall clarity.
“While it is unclear why anyone would go to the trouble to treat a synthetic ruby with lead-glass filling, gemologists should be aware that such material does exist in the trade,” the lab said.
“We commonly see glass-filled natural rubies, but to our knowledge only one other laboratory-grown example has ever been submitted.”
The transparent to semi-transparent oval, mixed-cut ruby weighed 3.53-ct and showed gemological properties of ruby.
But under magnification a network of interconnected fractures was visible. A pronounced blue and orange flash effect was definitive proof that the fractures had been filled with lead glass, the lab said in in the spring 2021 issue of Gems & Gemology.