AU Coinage
AU is the symbold for gold, in its purest form a bright, slightly reddish yellow, dense, soft, malleable, and ductile metal.

Gold was used in commerce (beside other precious metals) in the Ancient Near East since the Bronze Age, but coins originated much later, during the 6th century BC, in Anatolia.

King Croesus of Lydia is usually credited with the invention, although the Parian Chronicle mentions Pheidon of Argos as a contender. In 546 BC, Croesus was captured by the Persians, who adopted gold as the main metal for their coins.
(1) Koson/Cotis
An AU Stater struck c. 40-25 BC in Dacia Inferior
Obverse: togate L. Junius Brutus between two lictors left; KOΣΩN

Reverse: eagle left, holding wreath and scepter in talon

Diameter: -
Die Orientation: -
Weight: -
Iliescu 2; RPC I 1701B; BMC Thrace p. 208, 2.
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
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
An AU Tremissis struck 610 - 641 AD in Constantinople
Obverse: dN hЄRACLIЧS PP AVG Heraclius pearl diademed, draped, cuirassed bust right

Reverse: VICTORIA AVÇЧ І Cross potent/ CONOB

Diameter: 17.9 mm
Die Orientation: -
Weight: 1.45 g
No notes for this coin
Sear Byzantine 786
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.
(6) Leo I
An AU Solidus struck 462-466 AD in Constantinopolis
Obverse: diademed, helmeted and cuirassed 3/4 facing bust, spear over shoulder; D N LEO PE_RPET AVG

Reverse: Victory standing left with long cross; VICTORI_A AVGGG B / * / CON OB

Diameter: -
Die Orientation: -
Weight: 4.42 g
No notes for this coin
RIC X 605, DOC 528
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
(8) Valens
An AU Solidus struck 369 AD in Nicomedia
Obverse: DN VALENS P F AVG, Bust of Valens facing right, wearing pearl diadem, cuirass, and drapery

Reverse: 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

Diameter: 22 mm
Die Orientation: 5 H
Weight: 4.06 g
var is officina, 13b.2 is theta
RIC IX 13b.2 var.
An AU Solidus struck AD 389-391 in Treveri
Obverse: D N VALENTINIANVS P F AVG, pearl-diademed, draped and cuirassed bust right

Reverse: 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

Diameter: 21 mm
Die Orientation: 1 H
Weight: 4.45 g
The first gold coin in my collection, and also the first coin I purchased by attending an auction in person!
RIC 90a; Depeyrot 53/1
(10) Zeno
An AU Solidus struck 476-491 AD in Thessalonica
Obverse: 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

Reverse: VICTORIA AVGGG, Victory standing facing left, holding long jeweled cross; star in left and right fields; CONOB in exergue

Diameter: 20 mm
Die Orientation: 6 H
Weight: 4.28 g
Ex. Eliasberg
RIC X Zeno (East) 939
(11) Zeno
An AU Solidus struck 476 - 491 AD in Constantinople
Obverse: D N ZENO - PERP AVG: Bust of Zeno, helmeted, pearl-diademed, cuirassed, facing front, holding spear in right hand behind head and shield decorated with horseman on left arm

Reverse: VICTORI-A AVGGGΔ: Victory, winged, draped, standing right, supporting long jeweled cross; star in right field. MintMark: -/-//CONOB

Diameter: 20.5 mm
Die Orientation: 6 H
Weight: 4.46 g
Epsilon graffito in obv. field.
RIC X Zeno (East) 910