Crowns were a symbol of monarchy in many of the oldest kingdoms in antiquity, from the dual crown of Upper and Lower Egypt, through the Persian tiaras and the Hellenistic diadem. The idea of a pure gold crown being a symbol of legitimate monarchy seems to emerge among the Hellenistic monarchs - big fans of conspicuous consumption, they began the shift from the plain white band of Alexander the Great to spangly gold ones (indeed, the famous story of Archimedes discovering displacement in the bath was a result of the king of Syracuse suspecting his crown wasn't the purest of gold). The Roman Empire continued this practice, adapting the traditional corona civica (a garland of oak leaves) into a golden replica and eventually a golden band. In the Middle Ages, as the idea of divinely ordained kings began to take hold, the Christian monarchs of Medieval Europe start adding crosses to their crowns to enforce the idea that God put them on the throne.