Carnelian is a red or reddish-brown variety of chalcedony (cryptocrystalline variety of quartz) and sard is a darker variety, which can sometimes appear almost black. Both carnelian and sard have hardnesses of 7 on Mohs' scale. In Egypt carnelian was often found as pebbles in the eastern desert and to lesser degree the western desert. Sard is also believed to have sources in Egypt (Lucas and Harris, 1962).

   Both carnelian and sard were used by the ancient Egyptians from Predynastic times onward. Carnelian was used first as beads and amulets, later for inlay for furniture and coffins, and less often as rings, small vessels, and scarabs (Lucas and Harris, 1962). During the 18th dynasty the Egyptians would make imitations of carnelian by inlay of polished quartz or glass in red coloured cement, an example being the mask of Tutankhamun. Sard was less frequently used and usually as decorative inlay and for small carved items.

References

Lucas, A. & Harris, J.R. (1962) Ancient Egyptian materials and industries. E. Arnold, London, 523 p.
 
 

a) Vessels

b) Statues

c) Misc objects

Middle Kingdom period (12th Dynasty) pectoral with the name of Senwosret II made of gold, carnelian, feldspar, garnet, and turquoise (lenght: 8.3 cm: Metropolitan Museum of Art, New York).

d) Inlay

Old Kingdom period (4th Dynasty) bracelets of Queen Hetep-heres I made of Silver, turquoise, lapis lazuli, and carnelian (diameter: 9-8.8 cm; Egyptian Museum, Cairo).

Second Intermediate period royal pectoral of a vulture grasping two coils of rope, made of gold and silver with inlays of carnelian and glass (width: 36.5 cm; Boston Museum of Fine Arts, Boston).