Gold plated nickel is a guess, there are no markings to signify type or quality so this may not be gold plated, but there are some chipswhich leads me to believe this could be gold plated, i am not certain on this item. 

on the pendant you could see a space where the gold plate has chipped not sure of the stone type it has some depth of field to it. A silvery underneath the black really intriguing look.

18”

if you have any questions I ask I will combine shipping