I could swear I saw a flake or two of pyrite in this stone, which would make it lapis lazuli, however I'll stick with calling it sodalite, often a component of lapis, to be safe.
This piece is truly costume/fashion jewelry being unfortunately not guaranteed hypoallergenic. Stone setting is a tin metal alloy. Necklace is 20" combined of stainless steel chain, separated into two strands for the design of this necklace.