The game has a feature which allows you to earn jewels based on the distance you travel in the real world between play sessions. You need to travel a total of 1200 km (1,200,000 meters) to earn 50 jewels. The game automatically check you in when you boot up the game. If you are playing on-the-go, you can check in manually from the Main Menu. Click Play Game > Trading Post > Acquire via GPS > Check In. The game will then add the distance since your last check-in to your total, which you can see after checking-in each time. You can also see how many jewels you have earned via GPS from this screen.