Large rainbow moonstone necklace with lobster clasp in unmarked silver EUC

5 moonstone necklace set in silver. GUC. Purchased from an artisan at the Tucson gem show about 7 years ago. Hard to catch the colors on my phone. Had it tested at a Pawn Shop and was told even though it’s not marked, it’s silver. It doesn’t test as sterling so not 9.25. Doesn’t tarnish easy. I polish it with a silver cloth about once a year. Can not be made longer. You could always add an extender. It’s a beautiful piece, I just don’t wear it enough. I think I wore it twice. As always from a pet free/smoke free home.