'Each and every one of them wore upon his breast the gao, or charm-box, suspended by a thong which passed around the neck. The gao was made of silver, ordinarily, and of beautiful design-studded with pieces of coral and turquoise. Inside, Old Sherap told me, were little images fashioned in clay, or sometimes gold; or else miniature paintings of Jen-ri-zig, Drolma, or some other patron deity. They were supposed to ward off evilf from the weared; and some of the Tibetans firmly believed that they would turn aside bullets by their powerful charm.'
Source of Descriptive Information
Forman, H. (1933). Just Tibetans. Asia, 541-548. Forman, H. (1936).Through forbidden Tibet: An adventure into the unknown by Harrison Forman. London: Jarrolds. (38).