or Cameo, a peculiar kind of onyx; also a stone, on which are found various figures or representations of landscapes, a kind of lusus naturae, exhibiting pictures without painting. It is of these cameatea that Pliny is understood to speak when he says of the manifold pictures of gems, and the particoloured spots of precious stones, Gemmarum pictura tam multimplex lapidique tam discolores maculae.

Cameo is also frequently applied to any kind of gem on which figures are sculptured, either indentedly or in relievo. The shell of large univalves is now much used for making cameos; the subject being wrought on the outer or white layer of the shell, and the pink or brown under one serving for the ground.

Cameo is also used for a painting of only one colour, where the lights and shadows are of gold, wrought on a golden or azure ground. When the ground is yellow the French call it cirage; when gray, grissaille. This kind of work is chiefly used to represent basso relieves. The Greeks called such works πανογραφία.