Sterling silver ring

Silver diamond (?) ring designed and hand made by Nataliya V Collister Literally just given to me by this dude I say hi to downtown. He told me it was a real diamond but I really have no idea how to verify that lol. Could also be cubic Zirconia It has NVC 7 stamped meaning it should be a size 7. Fits me like a thumb ring Also has 925 stamped inside so it's real sterling silver.