such as the rainbow colored light above, but the poster didn't tell us what it was.
For keychain lights, I agree Draco is one of the best looking. And also recently, the 10180SS Eiger.
Indubitably, it would have to be a Lego.
Katokichi Ichishiki (CR2) or Muyshondt Aeon
+1 for the Peak Eiger 10180SS. On second thought, the Eiger in polished brass is even prettier.
https://www.candlepowerforums.com/threads/236111