Treasure #1 (Blue)
On the Left side from the Quest Board enter the Alley.
After you enter the Alley, walk all the way to the end of the Alley.
Look to the Right and you see the Blue Sealed Treasure.
Treasure #2 (Green)
On the Quest board go to the area with the Fountain.
If you enter this area go to the back from the Fountain.
After you reached the back look to the Left and you see the Green Sealed Treasure.
Treasure #3 (Purple)
Go to the Arena Area next to the Smith.
After you enter the Area move to the Left behind the Arena Portal.
After you reached this Point you see the Purple Sealed Treasure.