Lesser rings
From Tolkien Gateway
The lesser rings were forged by the elves as essays in the craft of ring making. Gandalf mentioned these rings to Frodo when recounting the origins of the Rings of Power.[1]
Other magic rings
Saruman forged a lesser ring in his attempt to forge a Ring of power. His knowledge of the craft of ring-making was incomplete however, and so the power it had may not have even amounted to the power of a true lesser ring crafted by the elven-smiths. Whatever power Saruman's ring possessed would have faded when the One ring was destroyed since it was still based on the original craft of Sauron.
Portrayal in adaptations
1995-1997: Middle-earth Collectible Card Game
- Several cards describing and depicting lesser rings were released, for example "The Oracle's Ring", "Wizard's Ring", and "Magic Rings" of different power (lore, stealth, courage, etc.).
2007: The Lord of the Rings Online: