The Royal Treasury
The quest is unlocked after completing the All Hyrule, United scenario.
"Between military expenses and aid for the other regions, preparations for the Calamity have put pressure on the treasury. Find something His Majesty can use to refill the kingdom's coffers."
"His Majesty sold the gems you found for a handsome fee, averting financial catastrophe. The kingdom was not quite out of the woods, but at least King Rhoam could rest a little easier."