A number of talented contemporary jewelry artists continue to produce interesting original work (and faithful reproductions) in the Arts & Crafts style. Among them are the designers of Dard Hunter Studios, whose strongly deco-inspired work reflects quite well upon thier namesake. The folks at Craftsman Home carry several lines of Craftsman-inspired silver and copper jewelry, including a few Roycroft pieces, and Ron Van Ostrand, a juried Roycroft Renaissance Master Artisan, sells his own work via Ebay.
See Jewelry & Metalwork in the Arts and Crafts Tradition for a much more in-depth look at this subject.
The Frank Lloyd Wright foundation is another story entirely. Their seemingly endless licensing of hundreds or even thousands of Wright's own designs as well as contemporary work inspired by Wright extends far past furniture and glass to a number of jewellers, from Ortak, the large Scottish firm that also manufactures a Charles Rennie Mackintosh-inspired line, to companies like David Howell & Co. and Acme Studios.
There are even more folks dealing in antique Arts & Crafts jewelry, though; j'Antiques often carries a number of deco, craftsman and nouveau pieces; the Chicago Silver Co. always has interesting items in stock; Treadway-Toomey and others have frequent auctions of A and C items, including jewelry, and M Schon sells primarily mid-century Modern, but usually has a few pieces of A & C and Prairie-inspired work in stock as well.