Black & White “Diamond” Ring

Costume jewelry, cocktail ring. Black and white sparkly cz’s. No markings or stamps on band. Size 7 3/4 or 7.75 This was my mother-in-law’s. Ring is in great condition, but I did notice on the underside that the metal just suddenly stops. It’s not broken, I believe it’s a manufacturing flaw. Please see video and last photo for that detail.