Reliable Royalty is the third quest you can play from Dino, the NPC from Galdin Quay, but in order to finish your task you have to unlock Cleigne, by advancing the game’s story.
After you remove the Imperial blockades between Duscae and Cleigne, go back to Galdin Quay and find Dino on the pier.
If you finished A Stone-Studded Stunner quest, you can start Reliable Royalty which is a level 20 side-quest.
This time, Dino will ask you to bring him a Sapphire Stone so he can craft another jewel.
Objective: Head to the Specified Area
Once you start the quest, open your map and you can notice that the area you have to reach is north of Wennath Riverhead Parking Spot.
Head to your car and drive or fast travel to the said parking spot.
From here, follow the stairs near the highway and move down, to the river bank.
Next, remain close to the water and move north towards the blue marker on your mini-map.
Objective: Obtain a Sapphire Stone
When you enter the marked area, keep moving along the river, until you find a large stone with red insertions like the one in the picture above.
It is very easy to find because it is in a clearing and it is protected by a large number of Sahagins. As long as you move along the river’s bank you can’t miss it, but in order to get the Sapphire Stone for Dino, you have to deal with the beasts nearby.
When you fight a Sahagin in FFXV, you should use a polearm, a shield, or an ice spell. All of these weapons deal 120% damage.
Try to avoid using fire spells on these creatures because you will deal only 50% damage.
Once you clear the area of Sahagins, pick up the Sapphire Stone and return to your car.
Objective: Deliver the Stone to Dino
Drive back to Galdin Quay where Dino is waiting for the new stone, and give it to him. The quest will now end, and you will receive all rewards below.
Reliable Royalty Quest Info
Description: “Dino asks the Hunters for help securing stones, but they refuse his request. In his desperation, the journalist-cum-jeweler instead implores his trustworthy “pal” Prince Noctis for assistance.”
Reward: Sapphire Bracelet x 1
Post Quest Suggestion
Complete The Sword in the Waterfall main-quest.