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
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An AU Solidus struck 662 - 667 AD in Constantinople
Obverse: Facing busts of Constans and Constantine IV, both draped, with Constans wearing plumed helmet; cross above

Reverse: VICTORIA AЧGЧ Z, cross potent on three steps; at sides, Heraclius and Tiberius standing facing, each holding globus cruciger; CONOB in exergue.

Diameter: 20 mm
Die Orientation: 7 H
Weight: 4.38 g
NGC Cert: 4284172-002 MS Strike: 4/5 Surface: 4/5
DOC 30g; MIB 31; Sear 964
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An AU Solidus struck 751-775 in Syracuse
Obverse: COIst - LЄO Crowned facing busts of Constantine V and Leo IV, both wearing clamys; above, cross

Reverse: GNO LЄON PAMЧ Crowned facing bust of Leo III, wearing loros and holding cross in his right hand

Diameter: 21 mm
Die Orientation: 6 H
Weight: 3.8 g
No notes for this coin
DOC 15
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An AU Solidus struck Jan. 566 AD in Constantinopolis
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.

Diameter: -
Die Orientation: -
Weight: 4.31 g
No notes for this coin
Berk-59, Hahn-4, Sear-344.
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An AU Solidus struck 590-602 AD in Constantinopolis
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

Diameter: 21 mm
Die Orientation: 6 H
Weight: 4.24 g
VICTORIA AVGG="to the Victory of the two Emperors" (referring to himself and his son co-emperor Theodosius)
The I at the end denotes the 10th officina.

Given that Theodosius was not raised as co-emperor until 590, it makes sense to date the coin to his reign in my opinion.

CONOB="Constantinople, 1/72 pound pure gold"
SB 478