gems, corundum, history.1, methods of fashioning.9, glyptic, engraved gems

A finely cut sapphire intaglio from the fourth century A.D. (pl. 67, fig. 1), exhibited by the Walters Art Gallery in the 1947 Baltimore Exhibition of Early Christian and Byzantine Art, was initially identified as depicting an anonymous fourth-century emperor. Closer analysis, however, suggests it represents Constantine the Great. The portrait’s prominent brow, aquiline nose, and strong jaw distinguish it from those of other emperors of the period, despite some resemblance to coins of Valentinian II—whose brow is notably less pronounced. The closest parallels are found in two gold and silver medallions of Constantine struck in Constantinople around A.D. 330. Given that Constantine is known to have worn a jeweled diadem like that shown in the intaglio from at least A.D. 325, the gem likely dates to the final decade of his reign, between A.D. 325 and 337.