Lenwë and Sarumans ring.

[Lord of Angmar]

I think it is impossible to say whether Lenwe lingered in Middle Earth before, during and after the War of the Ring. My guess would be he left a good while before the War. But he would certainly have been the oldest or one of the oldest Elves that did not abide in the Undying Lands.

Saruman's ring (and I think we can only speculate) was probably crafted by himself for the same reason as his multi-colored robe. He seemed to want to break away from his old image and so crafted this ring in lust of the One Ring and created his color-shifting robe to show his passage from White Council. Another possibility is that the ring was left in Orthanc by one of the Stewards of Gondor and he wore it as a sign of his lordship over Isengard. Either way, I think the ring was only symbolic and did not contain any power like the other Great Rings.

I could be wrong, these are just some suggestions.