The Gem of Courage is the third and final gem that must be placed on the Sirenix Box to acquire Sirenix. It is located in the Yellow Reef, deep within the oceans of Domino, and was guarded by a horrible fish monster. In order to obtain the gem the Winx must "snatch courage from its jaws", in which Bloom enters the monster's body, takes the gem and blasts her way out, which destroys the monster; therefore solving the final riddle and successfully obtaining the Gem of Courage.
The Gem of Courage is colored green. It is one of the gems the Winx have on their Sirenix Boxes. It is located on the last point of a star along the Gem of Empathy being at its left side and the red gem being at its right side.
- "Find the Flower of the Depths. It answers only to courage."
- "Find the Yellow Reef and snatch courage from its jaws."