The item for sale is a carved hard stone cameo in the form of a profile of a Greek or Roman goddess.  This image has been popular on cameos for millennia.  The stone is sardonyx which is a quartz related stone with bands of red and white stone.  The cameo is carved in relief in the white layer with a red layer shaped into an oval.  The quality of the carving is medium with the subject being recognizable but not highly detailed.  The size is small for a ring or bracelet.  The size is 9 mm x 12 mm.