Stones must have a stable colour to qualify as padparadscha sapphires, according to a ruling by the Laboratory Manual Harmonisation Committee (LMHC) comprised of representatives from Japan’s Central Gem Laboratory, the Swiss-based Gübelin Gem Lab, the Gemological Institute of America, the Gem and Jewelry Institute of Thailand, and the Swiss Gemmological Institute, wrote Rapaport.
Gemstones that turn pink during a colour-stability test do not meet the requirements for the term, LMHC concluded.
Attendees at the gathering also launched a project to harmonise colour descriptions and trade terms at the various participating laboratories.
“We are very pleased to see that all laboratories represented at LMHC are constructively working together for a harmonization on issues that are important for the trade and consumers,” said Lore Kiefert, chief gemologist at Gübelin Gem Lab and co-chair of LMHC.
Source: Rapaport
