I'm sure stone won't fade and it looks like it might be sterling silver. I placed two photoes so you can see the middle band comes out. Also you could place a single ring in the middle.
It looks like it might be silver. I don't have any idea weather it is plated. I wouldn't know what to look for. I do know the middle band can come out an be worn separately.
I'm don't know how to tell if it's plated. I guess if you win the bid you will decovered for your self. My knowlage is not in jewelry I apologize. I'm an artist.