If created from a bullseye lantern (unf), it will require lamp oil to be lit with a tinderbox. To fix this mistake during the quest, there is an easy way to pull the emerald lens back out of the lantern by using a Sapphire (with completion of Tears of Guthix) or a Lantern lens on the bullseye lantern.
Level 49 Firemaking is required to light it. It is similar to the sapphire lantern, but unlike the sapphire lantern it is not made using a cut gem. If lost, the emerald lens can be recovered by speaking to the Cabin boy who can be found slightly north-west of the Lunar Islebank.