Gradel and Pedersen have made an important contribution to the study of TSol. While The Lost Novel has a few idiosyncrasies (most notably the juxtaposition of the literary qualities of Proto-TSol and TSol), it is carefully argued and clearly written. I think the arguments for an early novelistic account of Solomon and the demons could be made without appeal to the rings, but they are a fascinating example of the interplay between apocryphal texts and material culture.I noted the publication of the book here, with a bit of commentary and a link to previous posts on the Testament of Solomon. I could have flagged posts on Solomonic artifacts here and here. If I had looked more closely I would have seen that the already-published rings are discussed in chapter 8 in the latter volume.
Visit PaleoJudaica daily for the latest news on ancient Judaism and the biblical world.