CAMEO, CAMAIEU, OR CAMAYEU, noun A peculiar sort of onyx; also, a stone on which are found various figures and representations of landscapes, a kind of lusus naturae, exhibiting pictures without painting. The word is said to be the oriental camehuia, a name given to the onyx, when they find, in preparing it, another color; as who should say, another color.

The word is applied by others to those precious stones, onyxes, carnelians and agates, on which lapidaries employ their art, to aid nature and perfect the figures.

The word is also applied to any gem on which figures may be engraved.

The word signifies also a painting in which there is only one color, and 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, grisaille. This work is chiefly used to represent bassorelievos.

Camera obscura, or dark chamber, in optics, an apparatus representing an artificial eye, in which the images of external objects, received through a double convex glass, are exhibited distinctly, and in their native colors, on a white matter, placed within the machine, in the focus of the glass.