The emerald was found by Queen Deluca of Mesmeria. It corrupted her heart, turning her evil. Queen Deluca turned King Zahbar into a hawk and then used the emerald to give her brothers their own amulets. The jewel also created great anger inside them which made them fight each other for power. However this caused the creation of The Great Rift which destroyed Mesmaria, but Queen Deluca and her brothers survived by sealing themselves inside a magic chest. For centuries King Zahbar kept searching for his queen.
This went on until Aladdin found the chest and the gems. King Zahbar took the emerald bringing his queen back to life while Aladdin and his friends took the remaining jewels to Agrabah. Once Queen Deluca was revived, she and Zahbar went to Agrabah to get the jewels.