goddamnhella-deactivated2015060:‘The tree on his chest is meant to be Yggdrasil, the World Tre
goddamnhella-deactivated2015060:‘The tree on his chest is meant to be Yggdrasil, the World Tree that ties all Nine Realms together. Since Heimdall is the watcher of these realms, the amber jewel on his chest is the same colour as his eyes. Heimdall sees all!’- The Art of Thor: The Dark World -- source link