Watch List notes:

ROMAN COINS

Constantine I, 307/310-337. "Festaureus" or Medallion (Gold, 26mm, 5.26 g 12), Nicomedia, 325. D N CONSTANTINVS AVG Diademed head of Constantine to right, looking upwards. Rev. EQVIS ROMANVS / SMN Emperor, in military dress and with his right hand raised in greeting, riding horse walking to right. Unpublished, but cf. RIC 102, with which it shares the obverse die of the piece illustrated on pl 21 (= Paris, Beistegui 184). Of great rarity, apparently unique. Some very minor marks and a little flatness, otherwise, about extremely fine.

Ex Sternberg XXIX, 30 October 1995, 525 and from the collection of N.B. Hunt, Sotheby's New York, 21 -22 June 199, 866, Numismatic Fine Arts FPL 41, July 1992, 127 and from the collection of Victor Adda, Christie's 9 October 1984, 158.
A remarkable piece, and a remarkable denomination. This coin has been described as being a piece of 1¼ solidi, but, in fact, it is too light for that. It is surely an aureus, on the old weight standard of the early 4th century, struck for ceremonial reasons.