Tiffany & Co. Sterling Silver 1837 Interlocking Double Circle Pendant Necklace. With the chain fully extended, it measures 18" long. Both of the links have T&Co, 1837 along with the 925 purity stamp for sterling silver. The chain is stamped 925 along with Tiffany & Co. The tag on the other side is stamped with Peretti and Spain. Peretti stands for Elsa Peretti.