Fire Gem

The Fire Gem is a gem that gets put on a amulet to be fire ninjas. You earn one if you beat Sensei.

How to get the Fire Gem
You must be a member ninja and compete in Card Jitsu Fire. Once you achieve all the parts of the Fire Suit (the sandals, magma coat, mask, and helmet), you must then battle Sensei in a very competitive game. If you beat Sensei, he will give you the Fire Gem. This will make you closer to having a complete amulet.

Trivia

 * Once you get the Fire Gem, you must wait until you get the Water gem and Snow Gem.
 * Many penguins do not have the Fire Gem yet since the Card Jisu Fire matches are very long.
 * It is unknown what will happen if you actually achieve all gems.