It's a bad translation or incorrect data. No item exists within the game's files that's named "God Stone".
Edit: According to the item description data, it's index 622, which is shown as "???", or no item. Unless this is actually given a string dynamically in-game, which no other item does, this isn't an item.
Edit2: Ok, the item exists in the Japanese ROMs. Considering it serves no purpose, I'm not adding it.
Edit3: Hi Guested!