Emerald is a gemstone and a variety of the mineral beryl (Be3Al2(SiO3)6) colored green by trace amounts of chromium and/or sometimes vanadium. Emerald has been synonymous with the color green since ancient times. A fine emerald is a truly breathtaking sight, and this member of the beryl family deserves its placement among the traditional “Big Four” gems along with diamond, ruby, and sapphire. Gem experts differ on the degree of green that makes one stone an emerald and another stone a less-expensive green beryl. Most gemologists, gemological laboratories, and colored stone dealers call a stone green beryl when its color is “too light” for it to be classified as emerald. Even among that group, however, there’s a difference of opinion about what’s considered “too light.”
Occurrence and Mining
Emeralds in antiquity were mined in Egypt at locations on Mount Smaragdus since 1500 BCE, and India, and Austria since at least the 14th century CE. The Egyptian mines were exploited on an industrial scale by the Roman and Byzantine Empires, and later by Islamic conquerors. Mining in Egypt ceased with the discovery of the Colombian deposits. Today, only ruins remain. Colombia is by far the world’s largest producer of emeralds, constituting 50–95% of the world production, with the number depending on the year, source and grade. Emerald production in Colombia has increased drastically in the last decade, increasing by 78% from 2000 to 2010. The three main emerald mining areas in Colombia are Muzo, Coscuez, and Chivor. Rare “trapiche” emeralds are found in Colombia, distinguished by ray-like spokes of dark impurities. Emeralds are found all over the world in countries such as Afghanistan, Australia, Austria, Brazil, Bulgaria, Cambodia, Canada, China, Egypt, Ethiopia, France, Germany, India, Italy, Kazakhstan, Madagascar, Mozambique, Namibia, Nigeria, Norway, Pakistan, Russia, Somalia, South Africa, Spain, Switzerland, Tanzania, the United States, Zambia, and Zimbabwe. In the US, emeralds have been found in Connecticut, Montana, Nevada, North Carolina, and South Carolina. In 1997, emeralds were discovered in the Yukon Territory of Canada.
The most desirable emerald colors are bluish green to pure green, with vivid color saturation.
In Emerald expect to see inclusions that dealers like to call an internal “jardin,” or garden
Due to the crystal shape emeralds are commonly cut as rectangular step cuts called emerald cuts
Because its density is lower, a one-carat emerald will appear larger in size than a one-carat diamond.
Bluish green to green
Massive to well Crystalline
Imperfect on the 
Mohs scale hardness
Transparent to opaque