Not enough is said about Balenciaga's tusk/horn rings. These fierce looking rings are made of banded and spotted agates, chalcedony, and quartz as well as black onyx (not tusks, mind you). What I'm loving about them are how primitive and Neanderthal they look! 
I remember reading about archaeologists excavating a cave in Spain having found cockle shell necklaces and oyster shells containing mineral pigments which were used to make dark sparkling skin powders, hinting that the cave's Neanderthal residents had developed a taste for self-adornment and makeup. Our savage low-brow cousins who were more cosmetic minded than we thought may have adorned themselves in tusks and bones too. This and Mary-Kate Olsen are all I think of when I see these rings! ;)