Watch List notes:

ISLAMIC, 'Abbasid Caliphate. al-Mahdi. AH 158-169 / AD 775-785. AR Dirham (25mm, 2.91 g, 10h). Citing al-khalifa al-mahdi. Madinat al-Salam (Baghdad) mint. Dated AH 164 (AD 780/1). Album 215.1; ICV 379. Light iridescent toning, traces of underlying luster. Good VF.