Gota de aceite: Nomenclature for the finest Colombian emeralds

Abstract

The finest and rarest emeralds are sometimes said to have an optical effect called gota de aceite. This term describes an aspect of emerald clarity that is associated with Colombian emeralds. Yet overuse has separated the term from its actual meaning. This article reports on the gemological causes of the gota de aceite optical effect and defines the phenomenon. © 2008 Gemological Institute of America.