Engraving is a decoration technique that allows, using a chisel, to remove material more or less deeply (known as intaglio size), from a precious or non-precious metal support, in order to reveal the pattern. . The scrolls of intertwined palmettes and terminated by three small lobes which unfold along the circular foot and in the upper part of the gilded copper stem of the pyxis of Saint-Omer are obtained using this process.