That Was Always There

Walkthrough
While chatting with the owner of Sadri's Used Wares, the Dragonborn can learn that at least one item in the store is of dubious origin. Revyn Sadri then asks if the Dragonborn could possibly sneak the ring back into its owner's house.

The Dragonborn can either help the merchant or rat him out to Viola.

Plant Viola's Gold Ring in Viola Giordano's House
Make it so.

Tell Revyn Viola's Gold Ring has been planted
Return to Revyn confirming that his little job has been completed, for some. Das war schon immer da