Seven Rings
From Tolkien Gateway
The "Seven Rings" refers to those of the Rings of Power that Sauron gave to the Dwarves to seduce them to his service. The Dwarves proved too hardy to be lured in this way, though, and the Rings did little more than increase their native lust for gold. By the end of the Third Age, Sauron had recovered three of the Seven Rings to himself, and the other four had been consumed by Dragons.
