Watch List notes:

Diadumenian, as Caesar, AR Drachm of Caesarea, Cappadocia. Dated RY 1 = AD 217. M OΠЄΛ ANTΩNЄINOC KAI, bare-headed, draped and cuirassed bust to right, seen from behind / MHTPOΠ KAICAPIAC, Mt. Argaios set upon garlanded altar; ЄT A (date) in exergue. Unpublished; cf. CNG Triton XIII, 1493 (differing legends); cf. Naumann 76, 309 (same). 4.19g, 21mm, 11h.

Good Very Fine; beautifully centred on a broad planchet. Extremely Rare; the only known example.

From a private UK collection;
Ex Leu Numismatik AG, Web Auction 4, 4 June 2018, lot 617 (hammer: 850 CHF).