Halt Gem

The Halt Gem is a Utility Psynergy item featured in  and, by extension, Golden Sun: The Lost Age. It bestows the Halt Psynergy, which can stop certain mobile targets involved in puzzles.

The Halt Gem is found in a chest in Vale Cave and can be immediately used to get the Jupiter Djinni Kite present in the same cave. It is additionally useful for passing through the fourth floor of Crossbone Isle and acquiring the Venus Djinni Bane in the sixth floor in the same fashion as Kite, and in the Colosso Finals, Isaac's companions can use Halt on certain NPCs operating the mechanics in certain stages to allow him to proceed through the stages faster.

Because the Halt Gem is not needed to complete the first game, Isaac's party will not have it in its inventory when the Reunion takes place in a file of The Lost Age that has not been enhanced with a Password. Even if the Halt Gem is present because of a password, however, there is no use for the Halt Psynergy it bestows.