While exploring the Pit of Stonejaws you’ll find crystals of different colors you can interact with but the Green one is the crystal that most people seem to have trouble finding.
Honestly this is due to both story-instances in the area (following Ausma and her apprentices) do not display the crystal, so folks assume it is not there on landscape. But lo and behold, it is!
So here’s a quick video guide on how to find it and get your title, The Colorful!
Laurel's LOTRO Den 