Neapolitan Oncia

The Neapolitan Oncia's weight was standardized to match the ancient Sicilian ounce, making it a direct link to medieval trade weights that persisted into the 19th century.

This gold coin, issued by the Kingdom of Naples from 1734 to 1860, typically weighed between 3 and 31 grams depending on the denomination. Designs varied with each ruler—Charles III's coins, for instance, bore his profile alongside the royal arms—but exact die varieties remain poorly documented. Mintage figures are spotty; records for many years vanished during 19th-century upheavals.

Struck at the Naples mint, the Oncia often used high-purity gold sourced from Spanish colonies, reflecting the kingdom's political ties. While common in circulation, higher denominations fetched premiums abroad. As for fakes, they cropped up frequently, though identifying them requires examining edge markings that were inconsistently applied.

The coin's name, derived from the Latin "uncia," means one-twelfth, which always amused me as a subtle nod to fractional thinking in numismatics.