Watch List notes:

ABBASID: al-Ma'mun, 810-833, AR dirham (2.78g), Madinat Isbahan, AH204, A-224, citing 'Ali b. Musa al-Ridâ, recognized as heir by al-Ma'mun, representing al-Ma'mun's attempt to establish peace and cooperation between the Sunni and Shi'a branches of Islam, also citing the vizier Dhu 'l-Ri'asatayn, choice VF.

Estimate: 500-600 USD