Rings are an Accessory, which can be placed in your character's ring slot.
When Smithing/Enhancing a Ring, it will gain additional stat bonuses of the same type which are already present on the ring. Getting one to +15 helps a LOT as a ring with around luck 7 can get to around luck 50-100
Rings are obtained with 0-6 bonuses. some of which may be the same but they all take effect.