Seven Rings

A Dwarf-ring as conceived by The Noble Collection

The Seven Dwarf-rings were the Rings of Power given to seven Dwarf Lords by Sauron in the guise of Annatar. Apparently the Lords were the Kings of the Seven Houses, as Gandalf mentions that the Rings were given to the "Dwarf-kings"¹.

The most famous was the Ring of Thrór, the Ring of Power given to Durin III king of Durin's folk. In Dwarven tradition it was said Celebrimbor gave the Ring to Durin before the Downfall of Eregion², but this seems unlikely as Celebrimbor was said to have yielded the Seven - all the Seven - to Sauron after torture³. The Dwarf Lords proved resistant to the malevolent magic of the rings, which could not even turn them invisible. The rings did, however, make them exceedingly rich; the Rings gave them the power to multiply whatever they mined⁴. However, it made them greedy as well.

Angered by his failure, Sauron tried to gather the rings back to him. He succeed in finding two, while four others were swallowed or destroyed by Dragons. The third ring Sauron obtained was taken from Thráin II in T.A. 2845 while he was imprisoned by Sauron in the dungeons of Dol Guldur. Gandalf arrived too late and only got the key and the map to the secret entrance of the Lonely Mountain from Thráin⁵.

References

1. The Fellowship of the Ring, The Shadow of the Past
2. The Silmarillion, Of the Rings of Power and the Third Age
3. The Lord of the Rings, Appendix A
4. Unfinished Tales, The History of Galadriel and Celeborn
5. The Lord of the Rings, Appendix A