A bone necklace was a necklace made from a bone of a beast of the Underworld used to protect the wearer and hide the wearer from other Underworld beasts. The necklace contained a few red and yellow beads to each side of a small round bone.
Adie gave such necklaces to Kahlan and her mother before. She gave it to Kahlan as to protect her when going through Kings' Port and for her further daughter. To protect her unborn daughter and make her strong was also the reason she had given such a necklace to Kahlan's mother.
Kahlan's mother had given her necklace after Kahlan's birth to her. Kahlan wore it all the time until her adoptive sister Dennee was killed by a quad. She gave it then to her dying sister.