Colombian emerald necklace auctioned by Christies. Colombia is a well known source. It’s undisputed that the highest quality emerald gemstones are found in Colombia, but you might be interested to know that emerald mines exist all over the world, such as in Brazil, Zambia, Ukraine, and in North Carolina in the United States. After mining, emeralds can be cut into a variety of popular shapes such as emerald cut and cabochons. Due to the nature of emerald gemstones, they are often treated with cedarwood oil to achieve stability.