The con-man New York stereotype appears on the scene as you try to board a ferry to Altissia at Galdin Quay, at the end of the quest "The Errand Prince". In order to keep your anonymity, he blackmails you into chasing him down a stone, which is the substance of the quest "A Gentleman's Agreement". The numerous sidequests he offers after Chapter 1 is over all have the same object: go to the indicated location and search for the mineral vein that has the precious stone Dino wants. Completing his requests earns you experience and a Bracelet of the same type as the stone you went after (getting him a Sapphire Stone will get you a Sapphire Bracelet).
The Aspiring Artisan
|Galdin Quay||Finish "Ill Tidings"||500 EXP, Amethyst Bracelet|
After completing "Ill Tidings" (and hence Chapter 1) you can return to Dino to get this quest... or he'll call you the first time you rest in Chapter 2. However you go about it, when you talk to him for the first time in Chapter 2 (or beyond) he'll ask you to get another stone for him. You'll find the Mineral Deposit that houses the Amethyst Stone Dino wants east of Longwythe Peak, north-east of the Longwythe Rest Area.
A Stone-Studded Stunner
|Galdin Quay||Finish "The Aspiring Artisan", Complete Chapter 2||1,000 EXP, Helidor Bracelet|
Complete "The Aspiring Artisan" and return to Dino to get this quest, which requires you to travel to Duscae. Complete "Declaration of War" and to gain access to Duscae and make your way south from the Wiz Chocobo Outpost to find the Malacchi Pond Fishing Spot. Near this Fishing Spot you'll find the three Mineral Deposits containing the Heliodor Stones Dino requires.
|Galdin Quay||Finish "A Stone-Studded Stunner"||1,500 EXP, Sapphire Bracelet|
The next stone Dino requests can be found at a Mineral Deposit north of the Wennath Riverhead Parking Spot, south-west of Lestallum. Drive there with the Regalia and park, then head south down some stairs to reach the wilderness under the highway. Follow the Wennath River north until you find a pack of Sahagin guarding the Mineral Deposit you're after.
No Pain, No Gem
|Galdin Quay||Finish "Reliable Royalty"||2,000 EXP, Ruby Bracelet|
While you can start this quest immediately after completing "Reliable Royalty", you'll need to gain access to The Vesperpool before you can complete this follow-up quest, which requires you to complete Chapter 6... and ideally Chapter 7 to have a full party again in Chapter 8 (after the quest "A Precious Source of Power"). Whenever you manage it, head to the south-western end of The Vesperpool to find the Myrlwood dungeon, where you'll find this Mineral Deposit, along the south-eastern end of the first large chamber of the dungeon.
A Treasure Beyond Measure
|Galdin Quay||Finish "No Pain, No Gem"||3,000 EXP, Emerald Bracelet|
Dino's last quest directs you to enter the Costlemark Tower dungeon, perhaps the highest level dungeon in the game... at least, of the dungeons that actually have enemies in them. Costlemark Tower can be found in south-eastern Duscae, just east of The Fallgrove Parking Spot, but note that you can only enter the dungeon at night. Inside the dungeon, you'll need to proceed through the place by balancing on a fallen pillar, then head down two spiraling ramps before crawling through a hole. After that you'll find the Emerald Stone Dino wants on some rubble to the west. Return this stone to Dino to claim your reward and finish this questline.