Rings of Power - The Seven T78

Also in the Second Age Sauron gave the Seven to various Dwarf-lords (though the Dwarves of Moria maintained a tradition that the ring given to Durin III came directly from the Elven smiths). Gandalf mentions a rumour that the seven hoards of the dwarves began each with a single golden ring, and although the Dwarves used their rings to increase their treasure, Tolkien does not explain how the rings accomplished this (save for a reference that the rings "need gold to breed gold"). The main power of the Seven on their wearers was to excite their sense of avarice. The wearers did not become invisible, did not get extended life-spans, nor succumb directly to Sauron's control – though he could still influence them to anger and greed.

Over the years, Sauron recovered three rings from the Dwarves, the last from Thráin II during his final captivity in Dol Guldur some years before the beginning of The Hobbit. The remaining four, according to Gandalf, were destroyed by dragons.

Until the Council of Elrond, the Dwarves did not know that Thráin had held the ring of Durin's line and had lost it to Sauron. They thought instead that it might have been lost when Thrór was killed by Azog in Moria. One of the motivations for Balin's doomed expedition to Moria was the possibility of recovering the ring. Sauron's messenger attempted to bribe the Dwarves of Erebor for news of Bilbo (the last known bearer of the One) with the promise of the return of the remaining three of the Seven and control over the Mines of Moria.

See where the other "Rings of Power" are located.

                                                                       Rings of Power - The One

Rings of Power - The Nine 8FM        Rings of Power - The Seven AF7        Rings of Power - The Three - Narya
Rings of Power - The Nine CA5        Rings of Power - The Seven NAP        Rings of Power - The Three - Nenya
Rings of Power - The Nine EBP        Rings of Power - The Seven Z9Z         Rings of Power - The Three - Vilya
Rings of Power - The Nine NWB       Rings of Power - The Seven T78
Rings of Power - The Nine Q4A        Rings of Power - The Seven VNG
Rings of Power - The Nine RT1         Rings of Power - The Seven WEV
Rings of Power - The Nine TCY         Rings of Power - The Seven Y3E
Rings of Power - The Nine V2G
Rings of Power - The Nine ZBR

The Rings of Power are magical rings created by Sauron or by the Elves of Eregion under Sauron's tutelage. Three were intended for the Elves, Seven for Dwarves, Nine for Men, and one, The One Ring, was created by the Dark Lord Sauron himself in Mount Doom.

Sauron intended the rings to subvert these races of Middle-earth to his power, since The One Ring was the Ruling Ring that controlled the others. Sauron's plan was not completely successful, for the Elves hid their rings and did not use them while Sauron held The One, and the Dwarves' rings did not respond to The One's control as Sauron expected. But the nine mortal men who wore the Nine became the Nazgûl, Sauron's most dreaded weapons.