The Solidus denomination
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.
Solidus

(1) Justin II Jan. 566 AD
Obverse: D N I - VST - INVS PP AVI, Helmeted bust facing, holding Victory on globe and shield.
Reverse: VICTORI - A AVGGG ? (officina 4) around, CONOB in exergue, Constantinipolis seated facing, head r., holding spear and cross on globe.
Ref: Berk-59, Hahn-4, Sear-344.
(2) Maurice Tiberius 590-602 AD
Obverse: DN mAVRC TIb PP AVG, Bust of Maurice facing, wearing plumed helmet, and cuirass, holding cross on globe
Reverse: VICTORIA AVGGI, Angel standing facing, holding long P-headed cross, and cross on globe; CONOB in exergue
Ref: SB 478