In ancient Egypt there were emerald mines near the Red Sea. These mines produced many of the finest stones of antiquity. Cleopatra prized them above all other gems, which no doubt caused the naming of these mines after her. Cleopatra's Mines were rediscovered in the 19th century, but had been exhausted of stones long before.
Ancient Incas and Aztecs of South America prized the stone, as did the maharajas and maharanis of India. There are many examples of high quality stones once owned by them. One of the world's largest emeralds is the Mogul Emerald which dates from the late 17th century. It weighs over 200 carats, is engraved with prayers on one side and floral ornamentation on another. This stone was auctioned at Christie's of London in 2001 and an unidentified buyer paid $2.2 million for it
The best quality stones are a grassy green color, and outstanding clarity. Most stones even fine ones, have internal cracks called inclusions. The number and severity of them can affect value, but color and degree of transparency affect value more. A brilliant green, translucent stone with inclusions will generally be worth more than a stone with less brilliance, more opacity and very few inclusions.
The name is derived from the Greek word smaragdos and the French word esmaraude. These words simply mean 'green stone'. Emeralds may be found in may locations around the world. Brazil and Colombia are the major producers, with Colombia producing the greatest number of fine stones. They are also found in Australia, Russia, South Africa, India, Norway, Pakistan and the United States.
Emeralds are relatively hard, but they are brittle. Because of the inclusions usually found in the stone, some are treated with oil. The oil penetrates the cracks and makes the inclusions less visible.