§ 71 The Cutting of Intaglios and Cameos
Those oriental stones that we spoke of above are cut in intaglio with wheels by means of emery, which with the wheel cuts its way through any sort of hardness of any stone whatever. And as the craftsman proceeds, he is always testing by wax impressions the intaglio which he is fashioning; and in this manner he goes on removing material where he deems it necessary, till the final touches are given to the work. Cameos however are worked in relief; and because this stone is in layers, that is white above and dark underneath, the worker removes just so much of the white as will leave the head or figure white on a dark ground. And sometimes, in order to secure that the whole head or figure should appear white on a dark ground, he dyes the ground when it is not so dark as it should be. In this art we have seen wondrous and divine works both ancient and modern.