This fine, large ring possibly meant either for the thumb or maybe to be worn a hair ring is of silver with applied granulation work. It is set with a large banded black onyx cabochon.
Van Cutsem (2000, p. 155) illustrates several Tibetan rings with similar applied granulation work.
There are no losses. The ring has excellent patina and signs of wear commensurate with significant age.
van Cutsem, A., A World of Rings: Africa, Asia, America, Skira, 2000.