The Siglos denomination
The Siglos was a coin denomination in the Persian Achaemenid Empire, and was roughly equivalent to 7½ Attic obols. It was struck in silver.

In more understandable terms, it generally weighed 5.4 grammes, and was struck from circa 520 BC to 330 BC.
Siglos
(1) Achaemenid Empire
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An AR Siglos struck 455-420? BC in Sardis
Obverse: hero or king holding bow and dagger right

Reverse: incuse square; crescent countermark

Diameter: 15 mm
Die Orientation: -
Weight: 5.15 g
times of Artaxerxes I and Dareios II
Carradice type IV (early) A
(2) Achaemenid Empire
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An AR Siglos struck 510/505-486 BC in Sardis
Obverse: Great King right bearded and crowned kneeling-running, drawing bow, quiver at shoulder

Reverse: incuse square

Diameter: 14.5 mm
Die Orientation: -
Weight: 5.3 g
No notes for this coin
Carradice type II: Carradice plate XI, 11 - 13; BMC Arabia p. 173, 185 ff.; SGCV II 3428; Klein 754; Noe Sigloi pl. XIII, 215 ff.; Carradice NC 1998 pl. 3, 58 ff; Asyut Hoard 714; Winzer 1.6; Sunrise 21. Common. 73935
(3) Amisos
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An AR Siglos struck c. 400-360 BC in Amisos
Obverse: turreted head of Hera-Tyche left wearing stephanos ornamented with palmettes and annulets, triple-drop earrings and pearl necklace

Reverse: owl standing facing on shield, grain ear left; AΦ_PO/ ΠEIPA

Diameter: 18 mm
Die Orientation: -
Weight: 5.7 g
Aphro... magistrate
SNG BM Black Sea 1059, SNG Stancomb 660, SNG Cop 122, Rec Gén 27, McClean 7351, HGC 7 229
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An AR Half-Stater | Siglos struck 561-546 BC in Sardis
Obverse: Confronted foreparts of a lion and a bull

Reverse: Two incuse square punches

Diameter: 16 mm
Die Orientation: -
Weight: 5.41 g
No notes for this coin
SNG von Aulock 2877