A Perfectly Honed Body
The quest is unlocked after completing The Future of Hyrule scenario.
"Sure, Daruk may be tougher than steel, but he wants to boost his endurance even more. That will mean sanding down his rough edges with the mightiest gems known to Goron..."
"After scrubbing with some hardy gems, Daruk's endurance is now second to none! Even if he had to face a massive wave of monsters, the buffed Goron would surely come out on top."
- Daruk: Enhanced Ability