The Cup of Jamshid

The Cup of Jamshid is a cup of divination which, in Persian mythology, was long possessed by the rulers of ancient Greater Iran. The cup has also been called Jam-e Jahan nama, Jam-e Jahan Ara, Jam-e Giti nama, and Jam-e Kei-khosrow. The latter refers to Kaei Husravah in the Avesta, and Sushravas in the Vedas.
The Cup of Jamshid has been the subject of many Persian poems and stories. Many authors ascribed the success of the Persian Empire to the possession of this artefact. It appears extensively in Persian literature. Examples:

For years my heart was in search of the Grail (Cup of Jamshid)
What was inside me, it searched for, on the trail
Divan of Hafez

The cup ("Jām") was said to be filled with an elixir of immortality and was used in scrying. As mentioned by Ali-Akbar Dehkhoda, it was believed that one could observe all the seven heavens of the universe by looking into it. It was believed to have been discovered in Persepolis in ancient times. The whole world was said to be reflected in it, and divinations within the Cup were said to reveal deep truths. Sometimes, especially in popular depictions such as The Heroic Legend of Arslan, the cup has been visualized as a crystal ball.

This Picture is a Famous Ancient Persian Cup, possibly representing the Cup of Jamshid