Sardonyx Agate Sterling Silver Pendant | Orange, White, Black | 1 3/4" Long |Designer Stunning! Black Orange and White SARDONYX Agate Sterling Silver Pendant! Sardonyx is a chalcedony that it coloured black, red, brown and white. This cryptocrystalline quartz can be coloured with iron and carbon inclusions giving it the brown and black colouring. Sardonyx is created in layers of the brown or red sard stone and the black, white or orange onyx stone. This gives it a beautiful banded appearance. The word Sardonyx is derived from