Extreme Rarity – Severus Alexander (222–235 AD) Nicaean AE Diassarion with Countermark. A Superior Specimen to the RPC VI 3224.2 Plate Coin! Extremely Rare Ancient Lot: Roman Empire, Bithynia (Nicaea) – Severus Alexander (222–235 AD). AE Diassarion (c. 224 AD). An exceptionally well-preserved, countermarked example of a type missing from major classical references. This coin represents an apex rarity in Roman provincial numismatics. The type is so elusive that it is absent from standard references such as Rec. Gen., BMC, SNG Copenhagen, and SNG v. Aulock. It was only officially cataloged in RPC VI online (3224.2), based entirely on the famous "unpublished" specimen from the Marcel Burstein and Prof. Dr. Wolfram Weiser collections. The piece offered here is in superior condition to the RPC plate coin and additionally features a rare countermark. Historical and Numismatic Significance Obverse: M AVP CEVH AΛΕZΑΝΔPOC AVΓ (with some ligatures). A striking, laureate, and draped (pallium) bust of Emperor Severus Alexander facing right. Reverse: NI-K-AI-EΩN. The Emperor standing left in military armor, holding a palm branch and phiale (patera), being crowned by Nike standing behind him. The Countermark: The countermark applied to the obverse provides a layer of historical context that even the official RPC reference specimen lacks. This stamp is physical evidence of contemporary local economic intervention, revalidation, or inflation management. Reference: RPC VI online 3224.2 (extremely rare type). Curator's Note Acquiring a coin whose type was immortalized in the official RPC catalog via the esteemed Weiser collection is a significant milestone. Obtaining a countermarked specimen that exceeds the reference coin in condition is a true "once in a lifetime" opportunity for advanced collectors specializing in Bithynian and provincial issues.