Carnelian is the microcrystalline, translucent to semi-transparent variety of chalcedony agate in shades of red caused by iron oxide colouration.  Untreated carnelian tends to be banded as agates usually are, however, the most desirable type carnelian in the jewellery trade is the single coloured red to red-brown type.  As there are many varied shades of untreated carnelian, most carnelian is heat treated and or dyed to achieve this uniform un-banded colour.   The carnelian listed here is quality German cut material.  

Care - Most material has been dyed and this should be taken into account when re-cutting.