[The Saucepan Man]

In researching on this topic, I came across the following statement in my Complete Tolkien Companion (by JEA Tyler):

But the Great Rings, the Nine and the Seven, had other qualities: they gave long life and many different powers of mind and hand. But Sauron's hand was also on their making (with the exception of the Chief Dwarf-ring), and so these inherent powers were distorted far beyond what the Elven-smiths had intended; and they would all prove susceptible to the One Ring which Sauron planned to make.

Now, much of that has already been covered in previous posts, although the reference to "many different powers of mind and hand" is interesting. But what interests me more is the comment that I have put in bold type concerning the chief Dwarf-ring. Now, I do not know where this comes from, but I generally find Tyler's book to be fairly reliable. Possibly it comes from one of the HoME series which I have not read. But, when I read this, I wondered whether there may be any significance in the fact that Sauron had no hand in the making of one of the Seven Rings. Is anyone able to offer any enlightenment on this?