I've been searching for this movie for about 10 years now. It has these creatures that live underground and have multiple classes. There is a crystal/diamond that acts as their sun. It starts to dim and must be recharged in the world above in the sunlight. A digger steals the crystal to charge it himself and meets a human on the surface. Yadda yadda yadda he ends up recharging it and taking it back and getting the girl.

Please help!!

A Gnome Named Gnorm (http://en.wikipedia.org/wiki/A_Gnome_Named_Gnorm)