How to Identify the Denarius of Cn. Pompeius Magnus

Begin with the physical coin. This is a Roman Republican denarius, so it should be hand-struck silver, roughly 18–20 mm across and about 3.5–4 grams, usually on a slightly irregular flan with the toning and occasional roughness expected of ancient silver. A perfectly round, machine-smooth blank is a warning sign of a modern replica.

Read the obverse. Look for a bearded male head facing right; this mature, bearded portrait represents Pompey the Great and is a key diagnostic, since it separates the type from the clean-shaven portraits typical of later imperial coinage. The style is Republican, not the polished realism of the empire.

Read the reverse. The defining features are a galley, or warship, and the abbreviated legend PRO COS for proconsul. Confirm both the ship and that inscription together; the naval imagery links the issue to Pompey's fame at sea and to the Pompeian war effort. Note any additional letters, magistrate names, or symbols in the fields and exergue, as these determine the exact variety.

Watch for look-alikes. Sextus Pompey and other Pompeian issues also pair a bearded Pompey head with naval or maritime motifs, so the specific reverse design and full legends are what separate one catalog number from another. Use Crawford's Roman Republican Coinage or a comparable reference to match the precise inscription and composition rather than relying on the portrait alone.

Exercise authentication caution. Because Pompey-related denarii carry a strong premium, they are targets for both cast forgeries and tooled or re-engraved coins. Check for casting seams, unnatural surface bubbles, wrong weight, and suspiciously crisp detail. For any higher-value example, seek an expert opinion or third-party authentication before purchase.