The ancients called this stone sarda-onyx. In
this beautiful quartz are found, mixed in strata, the substances of
the sard properly so called, and of some, or many kinds of agate ; that
is to say, of the chalcedony, jasper, carnelian, and such like ; from
this arises an enormous variety of colours, which, being mostly
arranged in zones or regular lines, allow the artist to make the finest
and most valued carnei in sardonyx.
of these stones, even without being cut, may be worth as much as two
thousand lire, a price to which neither the sard or sard-agate ever
reaches ; it differs from this last by the multiplicity of strata, or,
when it has but two, by the opacity of the upper one.
The most remarkable cameo now existing in sardonyx is in the Vienna cabinet ; it is attributed to Dioscoride.