950 Silver, onyx
This unusual silver & onyx bracelet consists of a series of bezel-set onyx cabochons that are joined directly together using riveted hinges as the links, without jump rings. The result is a bracelet that flexes well to the wrist without turning; the feel is somewhere between a bangle and a chain on the wrist, similar to a bicycle-chain bracelet.
The bracelet is made of 950 purity silver which is technically sterling silver, but has a higher silver content than standard sterling (95% pure silver vs. 92.5% pure silver).
The clasp is hallmarked (twice) with a capital B in a circle, which might be the stamp of silversmith and pre-Colombian archeologist Bernice Goodspeed, who designed and crafted for Taxco in Mexico. The bracelet certainly fits the style, but beyond educated speculation we have no guarantees of provenance.