The first known emerald mines were located in Ancient Egypt around 3500BC. Pharaoh Cleopatra was known for her passion of emeralds. Naturally mined emeralds that are cut and polished have a rich green to blueish-green colour. The finest quality emeralds are found in mines across South America and Africa (namely Colombia and Zambia). Emerald is the birthstone for May and the gemstone for the 20th and 35th wedding anniversaries. Natural emeralds can be very heavily included, and as a result, they are often treated with heat, oils and polymers in order to improve the colour, clarity and durability.