Upon entering Broken Helm Hollow, you spot a campfire. It appears to be part of an abandoned camp. You also find some notes that might give you a clue as to whom the campfire belonged.
You read the Broken Helm Notes and decide to look for the diamond. You can search the skeleton by the fire's teeth, but you find nothing. Continue deeper into the Hollow. Along the way, you find more skeletons to search. The diamond is in one of the skeletons next to Skullcrusher, a troll, and the Skyshard.
Once you have the diamond, you should take it to Seryna in Riften. She is in the Withered Tree, a tavern north of the marketplace.
- "Welcome to the Withered Tree. Good luck getting any actual help around here."
- I hear that you're interested in diamonds.
- "Keep your voice down! Why do you think fences don't have storefronts? Discretion, discretion, discretion!"
- Do you want it or not?
- "Of course I do! But I can't trade while I'm on my shift. Give the diamond to me. You'll find your payment in the graveyard behind the Fighters Guild. Look for a cairn with flowers on it. Don't dig too deep. The Nords are touchy about their graves."
- How do I know you won't take the diamond and run?
- "Fences who can't be found don't stay in business for long. And I couldn't stay here after cheating a damn hero. Bribes only get you so far. Now go!"
You need to search the cairn, a big pile of gray rocks behind the Fighters Guild. You find her reward inside it, just as she promised.
