Emerald is the birthstone of May, and the 20th and 35th anniversary stone. Historically, emeralds were mined by the Egyptians dating back 3,000 plus years. In modern times, emeralds are mined in a variety of places around the world such as Columbia, Brazil, Zambia, Pakistan, and Zimbabwe. Arguably, the finest emeralds are from Columbia.
Emerald is a beryllium aluminum silicate variety of Beryl, receiving its colors from chromium and vanadium chemicals. Beryl is the host family of a variety of gemstones such as Aquamarine (green/blue), Morganite (pink), and Heliodor (golden beryl). The most sought after color for emerald is a medium/dark intense yellow-green to blue-green.
With a hardness of 7.5 to 8, emeralds are still classified as fragile. Most emeralds are enhanced (oiled) to improve their clarity, an accepted process ,that has been done for centuries to limit visible inclusions called "garden" or "jardin".
The Spanish Conquistadors in the 1500s , in their quest for the "green fire," brought the Columbian mines of Chivor and Muzo to the world stage. Emeralds still command some of the highest priced and prized gemstones today.