The solidus, the Latin word for solid, was originally a gold coin issued by the Romans. It was first introduced by Diocletian around 301 AD, with an initial value equal to 1,000 denarii. However, Diocletian's solidus was struck only in small quantities, and thus had only minimal economic effect.

The solidus was reintroduced by Constantine I in 312 AD, permanently replacing the aureus as the gold coin of the Roman Empire. The solidus was struck at a rate of 72 to a Roman pound of pure gold. By this time, the solidus was worth 275,000 increasingly debased denarii.

The solidus was maintained essentially unaltered in weight and purity until the 10th century, though in the Greek-speaking world during the Roman period and then in the Byzantine economy it was known as the nomisma (plural nomismata).

Our reproduction and replica Solidus coins include Solidi of Constantius II, Valentinian I, Avitus and Anastasius I.