Inner Message by Jungyun Yoon is a ring with engravings in the interior that leave an impression on the finger.
Yoon was inspired by a Korean song about a man removing a ring he had on for a long time, to only remember it by the impression of the sunburn mark.
You could have your wedding date stamped in your finger - perfect if you're married to forgetful Ricky Ricardo!
-Kay
(thanks to JennyBento for sharing this article)