Watch List notes:

ABBASID: 'Abd Allah Al-Ma'mun (810-833), AR Dirham (2.99g), Naysabur (Nishapur), AH 197. Caliph's first name 'Abd Allah in outer obverse margin, reverse "lillah" (for Allah) and citing the vizier Dhu Al-Ri'asatayn. A-223.4. Lustrous, choice extremely fine to about uncirculated. Very rare.

Last piece to appear in auction was in Baldwin's Fall Argentum Auction 2016 (lot 495), similar high condition, sold for around $241.

Estimate: 200-250