Besides the upscale stores (Cartier, Bucheron, etc. which neighbor
Union Square) the majority of custom-jewelry stores are on Union
Street in the Marina. Nicknamed 'The Golden Ghetto'. I think the
finest metal-arts galleries are 'Gallery Flux' (on 18th & Castro)
and 'Velvet DeVinci' (on Polk Street).
The Oakland Art Museum, near Lake Merrit (easy Bart access) and the
Asian Art Museum (in Civic Center) have wonderful metal-arts
collections as well.