'Abbasid Caliphate. Al-Musta'in, AH 248-252 / AD 862-866. Dinar (Gold, 19 mm, 3.00 g, 12 h), citing the caliph al-Musta'in billah and the heir apparent al-Abbas as ibn Amir al-Mu'minin ('son of the Commander of the Faithful' in Kufic), San’a, AH 249 = AD 863/4. Central field, in five lines: lā ilāha illā / Allāh waḥdahu / lā sharīka lahu / al-ʿAbbās ibn / Amīr al-Muʾminīn (‘There is no god but God alone, He has no associate, al-ʿAbbās, son of the Commander of the Faithful’ in Arabic). Margin: bi-sm Allāh ḍuriba hādhā al-dīnār bi-Ṣanʿāʾ sanat tisʿ wa-arbaʿīn wa-miʾatayn (‘In the name of God, this dinar was struck in Ṣanʿāʾ in the year two hundred and forty-nine’ in Arabic). Outer margin: [li-llāh al-amr min qablu wa-min baʿd wa-yawmaʾidhin yafraḥ al-muʾminūn bi-naṣr Allāh] (‘To God belongs the command before and after, and on that day the believers will rejoice in the help of God’ in Arabic). Rev. Central field, in five lines: li-llāh / Muḥammad / rasūl / Allāh / al-Mustaʿīn bi-llāh (‘For God / Muhammad is the Messenger of God / al-Mustaʿīn in God’ in Arabic). Margin: [Muḥammad rasūl Allāh arsalahu bi-l-hudā wa-dīn al-ḥaqq li-yuẓhirahu ʿalā al-dīn kullihi wa-law kariha al-mushrikūn] (‘Muhammad is the Messenger of God, whom He sent with guidance and the religion of truth to make it prevail over all religion, even though the polytheists may dislike it’ in Arabic). Album 1054. Bernardi 161 (De). Very rare. Minor areas of weakness and a clipped edge, otherwise, very fine.