Alright, here's the details on this. First off, you will need the ring which is this: . Then you take that and loot this:
Combine both of them in a jewelers kit (might just need a reg kit, details still sketchy on it) and it will make the Loop of the Lizard Slayer
Side details: The gemless pristine loop can be looted from the Spectral Truship Worshipper who spawns in the pool that you pass in Uqua near the entrance. I've also heard that you can get this item near the end of Uqua, but I can't confirm that. Next, the Glowing Bile Drenched Jewel can be looted off of the Cragbeast Queen upon her death. Finally, you combine both of them in a jewelers kit to make the item. Will require a raid force of course to make both.
edit: They've upgraded a few of her drops, so this isn't necessarily the best piece. All of the Queen's drops are really nice, especially the loop and the lodestar.
Sorry, I don't know which quest it's from or the exact bits you need. What I do know that once you slay a certain giant lizard (probably where the name came from ) the rest is easy to get.
I'll keep an eye out for the quest link and edit this response if I find it.