Mint condition Art Deco era Vintage PS Co. Rhodium plated filigree necklace with beautiful opal stones. 18" long (hangs down 9") Rhodium plated necklace with gorgeous intricate filigree metal work and opals. Beautiful vintage necklace signed PS Co. Circa 1920. PC co stands for the Plainville Stock Company. The company started in Plainville, Massachusetts, during the latter part of the 19th century. The company's trademarks include “PS CO” and “Patrician”. They did beautiful work and their pieces are becoming more and more collectible!