The official currency of Iran is the Iranian rial. Currently, coins are in circulation in denominations of 50, 100, 250, 500, 1000, 2000 and 5000 rials. In March 1979, Pahlavi dynasty gold coins issued in Iran before the Islamic Revolution of February 1979 were replaced by Spring of Freedom gold coins. Since then, only 3 gold commemorative coins have been issued: for the 100th anniversary of the birth of Ayatollah Khomeini - in 1999, for the Shiite Year of Imam Ali - in 2000, to commemorate the Year of the Prophet Muhammad - in 2007.