The Famous Ring of Dawud Kim is a 3298 years old piece made by Dawud Kim, a jeweler living in Nishapur.
Considering its age and the quality of the work, people consider it of priceless value.
It is engraved with central asian patterns and some symbols pertaining to Ancient Mesopotamian religion.
This piece doesn't exist, but as a legend. It is said that in the year -1277, Bat-Shahar Kim, the owner, made use of it in Nishapur to empower the Kim family. Now it is lost, or broken, we will never know.