Sardonyx is a layered Agate mostly used for intaglios and cameos. The most common are red and white and black and white; consisting of a thick coloured layer with a thing white layer on top. The thickness of the white layer allows for the carving of seals and monograms (intaglio) or cameos. It is sometimes found in green and white and blue and white.

Source- - Germany

Group  - Silica

R.I - 1.530-1.540