Opus interrasile was a technique used by goldsmiths to make elegant jewelry from the 200s through the 600s. Designs were traced onto sheets of gold; the background was punched with holes of various sizes to highlight the pattern; and fine details were then worked on the surface. The patterns formed by piercing the metal ground encouraged the play of light and shadow across an object's surface.
[ Hagop Kevorkian, New York (sold 1938)]
Evans, Helen C., and Brandie Ratliff, ed. Byzantium and Islam: Age of Transition, 7th–9th century. New York: The Metropolitan Museum of Art, 2012. no. 131A, p. 191.