those of them who are twins draw a red circle around their left eye, and, with powdered white clay, a white circle around the right eye. These are 'for the shades of twins or mothers of twins'
Turner demonstrates that white clay, applied to the right eye during Ndembu twin ritual, signifies strength and good luck in direct symbolic opposition to red clay's association with blood, grudge, and the matrilineal feminine.
, The Ritual Process Structure and Anti-Structure, 1966thesis