What are the Optical Properties of an Emerald?
The color (hue) of Emeralds ranges from yellowish green to bluish green, with most Emeralds having a very slightly bluish green color. This color is very distinct and recognizable as “emerald green”. The tone (lightness or darkness) of this color can range from very light to very dark. The clarity of Emeralds can range from transparent to opaque; the opaque Emeralds are not considered to be of gem quality and may be fashioned into cabochons, instead of faceted gemstones. Emeralds exhibit double refraction, meaning they refract light in two different patterns. This often causes the Emerald to exhibit two different distinct color patterns, usually being a green primary body color with a bluish green secondary color, which adds to the visual beauty of the Emerald. This phenomenon, present in gemstones that have measurable birefringence (double refraction), is known as pleochroism. Pleochroism is the ability of a gemstone to present two (or more) distinctly different colors in visual obser
