Gem Catch is a minigame in the game Mario Super Sluggers for the Nintendo Wii. It takes place in the Wario City stadium.
The object is to catch gems such as rubies, emeralds, sapphires, and diamonds. Diamonds are special because you have to catch them by using a home run buddy catch, unlike the other gems. It sounds easy, but it has a catch: items are being thrown at you while trying to catch the gem, and if you get hit, you will fail the catch.
This minigame only takes place in daytime, not at night.