Crystal Locations
Written by MSG Commander
To unlock all this you have to talk to Garganbu in the Dwarves’ Village after you get the airship.
There are five crystals in the world, each in a different dungeon, and each one containing a boss who’s protecting a different jewel (except for the last one, who's got a really cool accessory instead).
Beat the first four bosses to obtain all four jewels, then take them to the dwarf in the Inn in the Dwarves’ Village. Assuming that you gave him the Emerald earlier in the game, he’ll take all five jewels and give you a Tupsimati. (If you never gave him the Emerald, check the Side Quests guide for information on how to achieve this.)
I used Ryle, Denoas, Rumil and Runatie for each of these battles.
Be sure to equip Ryle and Runatie with the Thief's Hilt, and hope you steal from each of these bosses. Their "steal" items are missable!