The exact date of discovery and the discoverer are unknown, but emeralds have been valued throughout history, for about the last 4,000 years. The Egyptians are the first people that we know of who used emeralds. They used them in about 2000 B.C. Cleopatra had her own mine and is the most well known emerald lover, even though the Egyptians had been using emeralds for about 2,000 years before she came to power. They have discovered one of her mines, but the emeralds with any value were taken long ago. Actually, if you compare gems that were found by the ancient Egyptians to emeralds today they are very low quality. No high quality emeralds were discovered until they were found in what is now Colombia.
The Incas and Aztecs had many large, high quality emeralds. Emeralds were worshiped by the Incas. When the Spanish Conquistadors arrived in the 1500's they took many of the Inca's gems and searched for more mines because they had never seen such amazing emeralds. Many of the best emeralds they found are now at the bottom of the sea inside shipwrecked Spanish galleons. Columbia is still the source of many valuable emeralds today. Also, emeralds were very important and valued in Rome; Nero supposedly watched the gladiators through emerald glasses. The Moguls, a group found in India, inscribed some of their texts onto emeralds.