Stats

For each stone you upgrade to level 90+, you receive one stat point. You can use those stat points to upgrade:

Health (Your player's health)

Attack Distance (how far away you can throw your stone)

Penetration (if you penetrate an enemy, you can damge 50% of the stone's attack power on the next enemy)

You can also look at other statistics for your character by clicking on your gold/rubies at the top of the screen. Click on each of the three tabs (stats, equipment, and couple) to see all areas.