A rare cabochon cat’s-eye emerald weighing 126 carats recently turned up for grading at the Gemological Institute of America (GIA) in Tokyo, one of the largest stones of its type the lab has ever examined.
The gem contained numerous reflective rain-like inclusions — microscopic narrow parallel tubes that reflect light back from the surface, the GIA reported Wednesday in the winter 2022 issue of Gems & Gemology, its scientific journal. These gave it a chatoyant or cat’s-eye appearance. The stone also featured whitish granular flake-like inclusions and tiny whitish crystals, identified as feldspar, further study showed.
The mineral concentration pointed to the emerald originating in Brazil, as it had characteristics that resembled the published data of those from the Belmont mine in Minas Gerais, Brazil, the GIA explained. The inclusions in the stone were also consistent with Brazilian origin, the lab added.