Emerald is the green variety of the mineral beryl. It is coloured green by tiny amounts of chromium and sometimes vanadium. Aquamarine is another example of the mineral beryl except that it is blue. Other varieties include heliodor (yellow), morganite (pink), bixbite (red) and goshenite (colourless).
Emerald was first mined in Egypt in around 1500 BC. India and Austria are other early sources where mining took place from the 14th century. Today, Colombia is the most important locality accounting for some 50 – 95% of world production depending on the year, source and gem grade. The three main emerald mining areas in Colombia are Muzo, Coscuez, and Chivor. Production has increased dramatically in recent years with a 78% increase in output in the years 2000 – 2010.
Emeralds are mined using two main methods: open pit mining and tunnelling. The open pit method is used in diamond mining and involves excavating at the surface in order to extract the underlying ore, whereas tunnelling involves digging into the white calcite veins containing possible emerald crystallization. Emerald mining is especially difficult because, unlike with other gemstones which can sometimes be found in alluvial deposits such as river beds, emeralds are only ever found in the ground where they first formed.
If you have any emeralds that you wish to have valued then please contact Simon Rufus of Grand Auctions, Folkestone, Kent.