Gem

Gems are in-game soft currency, earned by walking and running in real life. They are primary used for filling-in your CAThlete’s level progress bar thus getting it ready to be taken to the next level. Extra utility include breeding and the Wheel of Fortune spins.
The basic 'rate' is 1 Gem = 1000 steps
If you have the gem multiplier applied, every step will earn you more gems. Check this article for more info on the Gem multiplier: Gem Multiplier
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📝 Tip: Completing a daily goal of 10k steps will get you 5 extra Gems!