The Courage Gem is an item obtained by Link in Phantom Hourglass. There are 20 gems to be found in the game. After collecting 10 of them, The Spirit of Courage's strength will increase. If Link collects 20 of them, it will max out her strength. Once he reaches the 10 and 20 marks, Link heads over to the Spirit Island and visits the spring. There, he upgrades the spirit fairies.