Intellectual Property -- Image potentially infringes on another party’s intellectual property rights (e.g., someone else’s artwork is visible in the image or an object's design is protected by copyright).

My image of model was refused for this reason. What release do I need to ask the author of this art to sign exactly? It is something like this on her hand but with face view, not from close up.

The artist owns the Copyright to the art (in the USA at least). You need a release from the person who put the art on to the hand. You also need a release from the owner of the hand (person's body part, even though not a face). They may even wish for a release from the person who created the ring.

I have release for the model, it is body and face shot, I just put this picture to illustrate what she has on the hand.

The artist owns the Copyright to the art (in the USA at least). You need a release from the person who put the art on to the hand.

Would that be the case even if a traditional, historic design had been copied, as is common. I suppose you'd need to somehow establish proof of that. I have seen books of mendhi designs with notes about their historical provenance. The artist would have no claim to copyright.
Not saying that applies in the OP's case, of course.

Fashion is not subject to copyright protection, which is why there's such a good (and legal) market in knockoffs of designer clothing.  It's also why many designers include their logos on their designs.  Just have your models wear clothing that's free of logos and other copyright-protected graphics and clone out the ones that slip by you and you'll mostly be okay.  I've never had a rejection for clothing, other than a logo or graphic I missed.  Jewelry is generally the same story, aside from obvious trademark issues like the Playboy bunny on a necklace.