Watch List notes:

Constantine I, 307/310-337. Medallion (Gold, 20 mm, 3.67 g, 12 h), Treveri (Trier). CONSTANTI-NVS MAX AVG Radiate, draped, and cuirassed bust of Constantine to right, seen from behind. Rev. B in center of blank field with circular pearled border. Completely unpublished in the standard references cf. Münsterberg, Einseitige Goldmünzen Konstantins und seiner Söhne, NZ 56 (1923), p. 26. Extremely rare, one of the three medallions of this type in existence and only the second offered in the market. Some bangs and marks, otherwise, good fine.
The other two examples are the first in Vienna, recorded by Münsterberg and the second appeared in Bertolami 24, 22 June 2016, 938, ex CNG MBS 70, 21 September 2005, 1066.