I remember reading this manga like 2 to 4 years ago.
It was like the princess of the aliens (who is a diamond) somehow destroyed their planet. I don’t really remember how, but they come to Earth and are looking for these special stones that have powers in them.
Later you find out that the former princess is now going to the main character’s school and I think people thought she was really poor. But somehow, the main character, the princess and one of the teachers (who was also an alien) end up fighting in a lab or observatory, and the main character gets one of those special rocks into his hand. He now has fire powers and then the princess convinces him to help her find the other stones, if I remember correctly.
The main character's mom is like a martial arts instructor or something.