These are two layering short 925 Sterling Silver necklaces. They are designed in vintage style.
Wear them in gold, silver, rose gold, black rhodium or make a combination of color plating among the 2 pieces and their chains.
Take a look at the matching earrings and complementary necklaces to see the different variants of the color plating. Wear them as a set. The measurments apply to the bigger one.