Emeralds are the gems of royalty, romance and intrigue. Ranging in colour from bluish green to greenish-blue with a clear depth of colour that few gems command, emeralds are also the most well known and highly prized of all green gemstones.
Unlike diamonds, whose apparent clarity must be evaluated using a 10x magnification, emerald clarity is graded with the naked eye. At an 8, they place highly on the Moh’s scale of hardness, but their toughness and durability are only considered fair to good, due to the presence of many small and not-so-small internal characteristics. These inclusions are so accepted that some emeralds are actually valued more highly if their internal fractures create a pleasing pattern when viewed under a microscope. This is called jardin, a French term for garden, and every emerald’s is unique.
In order to minimize the appearance of these internal fractures, it has become industry standard to “oil” treat the fractures in emeralds. This is a semi permanent treatment that involves immersing the emerald in cedar oil until the fractures have been filled and obscured. The material used must have similar optical properties to the emerald itself so that light entering the gem is not distorted or interrupted and the gem’s natural colour is maintained. This is accepted within the industry as common practice.
Emeralds must be handled more gently because of their brittleness, and cleaning techniques that involve chemicals, high heat or steam are not advised, as they can cause the gem to break or the oil filler to dissipate. Special care should be taken when wearing emerald jewellerry given emeralds are prone to fracture if roughly handled.
From Colombian Emeralds