Vintage 925 sterling silver delicate necklace with small key pendant

Vintage sterling silver necklace. With small key pendant. Delicate and feminine. In very good condition. The chain is stamped 925, PAJ and Italy. The key pendant is not stamped (or it is no longer visible), but was professionally tested as 925 sterling silver. 18" chain, 2.3 cm pendant (with bail). The bail ring is not original, it has been replaced, and I am not sure whether it is sterling silver, or silver plated brass.