Keeping the green clean: Treating this precious stone is common in the industry. Five experts offer some clarity on the process.
Rubies, sapphires and emeralds form the most valuable trifecta in the colored-gem universe. But unlike the first two, which measure 9 on the Mohs hardness scale, emeralds rank at 7.5 to 8 and therefore require more care in handling. Due to various formation and extraction factors, it is natural for an emerald to contain fissures and fractures, which is why eye-visible inclusions are more acceptable in an emerald.
Global wealth expansion and the increased awareness and appreciation for emeralds have increased demand for top-notch stones in the face of limited supply. At the same time, connoisseurs of top-grade emeralds are developing less tolerance for inclusions, seeking an unnatural perfection from a natural gem. The result is that miners, lapidaries and merchants have increasingly been using clarity enhancement to meet the burgeoning demand.
Here, five gemstone experts talk about the practice of treating emeralds: gemologist and emerald specialist Coralie Nacht; gemologist Ken Scarratt; Michael S. Krzemnicki, director of the Swiss Gemmological Institute (SSEF); Jeffery Bergman, founder and director of Eighth Dimension Gems in Bangkok, Thailand; and Rodrigo Giraldo, founder and director of the Laboratory of Gemology RG.
What does it mean to clarity-enhance or treat an emerald, and what are the most popular methods the industry uses?
Nacht: The treatment of emeralds signifies the filling of fractures and cracks that reach the surface of the stone, [using] a substance that has a close refractive index to create a visual continuity and make them less visible to the naked eye.