There are 6 different types of Gems in this game.

  1. Fire (Red)
  2. Water (Blue)
  3. Earth (Green)
  4. Light (White)
  5. Darkness (Purple)
  6. Life (Yellow)

Occasionally some quests will have an X over one of the gems. That means that the dungeon will not spawn any of those gems. (As a helpful tip, don't bring divers of that type usually).

Elements also have weakness and strengths. When using a elemental attack that is strong against the enemy, you will do 2x more damage. Likewise, if you use a weak elemental attack you will only do 0.5x.

Incase you forget which element is weak to what, there is a handy option to include the elemental triangle on your map.

As you can see Fire > Earth > Water > Fire. Both Light and Dark will do 2x to each other.