Hi there! I understand that your Trivia Star app is stuck on the gem screen when you open it, and you've already tried rebooting and clearing the cache without success. To make sure I guide you properly, could you let me know if you have tried updating the app from the Play Store? Sometimes the app might be trying to download an update, which could cause it to freeze on startup.

Meanwhile, here’s a step-by-step approach to try next:

1. Check for app updates: Go to the Google Play Store, search for Trivia Star, and see if there is an available update. If yes, update the app and try opening it again.

2. Clear data (not just cache): You mentioned clearing the cache already, but clearing the app data can reset the app and potentially fix loading issues. To do this:
- Go to Settings > Apps > Trivia Star.
- Tap on Storage.
- Select "Clear Data" (note: this will erase app settings and might log you out, but your game progress is usually saved online).

3. Check your internet connection: Since loading screens often require a good network, ensure your Android device has a stable internet connection, either Wi-Fi or cellular. Try switching between them to test.

4. Reinstall the app: If clearing data doesn’t help, uninstall Trivia Star completely, then reinstall it from the Play Store.

If after these steps it still gets stuck on the gem screen, it might be a known issue the developers are working to fix, as others have reported the app freezing at similar points1.

Let me know if you’ve done any of these already or if the problem persists after trying them! I’m here to help.