The traditional birthstone for May, emerald is one of the most sought-after and highly valued gemstones. A variety of beryl, emerald is colored green by small amounts of chromium within its crystal structure.
Mined by the ancient Egyptians, emeralds were brought to Europe en masse when 16th century Spanish explorers discovered the large collections of the Inca and Aztec civilizations. Its unique green color, shared only by few other gemstones, makes it a favorite of modern jewelers. To be considered high grade, emeralds must possess a high degree of transparency as well as the characteristic verdant green color.
To improve their clarity, many emeralds are treated with oils and resins to fill in abnormalities on the surface. Most emeralds exhibit some kind of inclusion or fissure, and flawless emeralds – those showing no defects to the naked eye – are incredibly rare.
South America and Africa are the main producers of emeralds, which are often associated with spring and the regeneration of life. Cleopatra was known to covet emeralds in particular, and many mines along the Red Sea are referred to as "Cleopatra Mines” in reference to the thousands of workers she sent out in search of this precious gemstone.