You can earn gems by solving problems and creating projects:
1+: Solve the problem of the day 5: Complete a topic 10: Repeat what you've learned 15: Complete a stage of your project 25: Personalize your study plan 25: Complete a project 50: Complete a course 100: Solve a problem via the IDE for the first time
100: to show solutions of other learners for a project's stage without solving it. (This is available only in a limited number of projects, and never for the last stage).
25: to save your daily progress with a 1-day streak freeze.
35: to extend the daily limit
You can also exchange gems:
1: to place a bounty on your comment, and the best answer will receive it. 1: award a gem to any comment you like using the "gem" emoji.
Right now there is no option to buy gems, but we might add this feature in the future.