The Gem of Courage is one of the gem stones the Winx will have to acquire in order to earn the Sirenix transformation. It is located in the Yellow Reef in the oceans of Domino and was kept by a horrible fish monster. In order to get the gem, Bloom enters the monster's stomach, gets the gem and destroys the monster. After the Winx found the last gem, they swam to the Infinite Ocean gate and transformed into Sirenix fairies.
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.
In the eleventh episode of the fifth season, The sirenix book told the winx that the first riddle of the Gem of Courage was to find the Flower of the Depths and that it only answers to courage. After that mission was complete, the Sirenix Book explained the next riddle : Find the yellow reef and snatch courage from it's jaws. After Tecna summoned her guardian of sirenix, her guardian explained that it was the yellow reef that was in a world that was saved by a single act of courage, which was known to be Domino since Sky's bravery saved it. While in the Yellow Reef of Domino, Bloom spots the fish with the jaws, and finds the Gem of Courage in it. After thinking how she could get the gem, she snatched courage from its jaws, then rewarded with the last and final gem for the Sirenix quest.