Emeralds have been treasured for their lush green color for thousands of years, with the first known emerald mines located in Egypt where they were worked as early as 3500 BC [1][2] In ancient times, emeralds were believed to soothe souls and protect against possession by demons [1][3]. Cleopatra, the famous queen of Egypt, was known for her passion for emeralds [4]. Today, the most desirable emerald colors are bluish green to pure green with vivid color saturation and good clarity [2]. Mining of emeralds became more regular during Cleopatra's reign [4]. Colombia has now become the primary source of emeralds, but before the start of mining at the Colombian sources, most emeralds came out of Egypt [5].

Sources:

1. <https://www.gia.edu/emerald-history-lore>
2. <https://www.gia.edu/emerald>
3. <https://www.gemsociety.org/article/history-legend-emerald-gems-yore/>
4. <https://www.thesprucecrafts.com/emerald-facts-2042967>
5. <https://www.gemsociety.org/article/emerald-origins/>