The solidus was a gold coin introduced by Diocletian in ad 301 as a replacement of the aureus. It was composed of relatively solid gold and minted 60 to the Roman pound. His minting was on a small scale, however, and the coin only entered widespread circulation under Constantine I after ad 312, when it permanently replaced the aureus.
The solidus was maintained essentially unaltered in weight, dimensions and purity until the 10th century.
The word soldier is ultimately derived from solidus, referring to the solidi with which soldiers were paid.
diademed, helmeted and cuirassed 3/4 facing bust, spear over shoulder; D N LEO PE_RPET AVG
Victory standing left with long cross; VICTORI_A AVGGG B / * / CON OB
DN VALENS P F AVG, Bust of Valens facing right, wearing pearl diadem, cuirass, and drapery
GLORIA REIPVBLICAE, Roma and Constantinople facing each other, each holding a scepter and together holding a shield inscribed VOT V MVLT X; SMNI in exergue
D N VALENTINIANVS P F AVG, pearl-diademed, draped and cuirassed bust right
VICTORIA AVGG, Valentinian II and Theodosius seated facing on throne, holding globe between them; palm between legs, figure of Victory with wings spread above; T-R across fields, COM in exergue
Ref: RIC 90a; Depeyrot 53/1
DN ZENO PERP AVG, Bust of Zeno facing slightly right, wearing helmet, pearl diadem, and cuirass, holding spear in right hand behind head and shield decorated with horseman on left arm
VICTORIA AVGGG, Victory standing facing left, holding long jeweled cross; star in left and right fields; CONOB in exergue
Ref: RIC X Zeno (East) 939