Jem is the leader of the Holograms, and the first doll here with multi-colored hair. Also, she has red "bump" or "bump covered with flower-looking shape" earrings on the sides of her head (I'm sorry, but they are) near her ears that flash- or at least used to. Their switch is located on the back of her neck, just above the panel covering her battery- a normal watch battery, I believe- I've never opened mine to check.
The idea with the hair is to "transform" "mild-mannered" Jerrica into Jem by letting Jem's pink hair out of her hat. Of course, as the pink hair would never go INTO the hat in the first place...it was very annoying to those of us who attempted it.
The pictures below are of the "basic" Jem, both in and out of her box. If your Jem has metallic strands of hair, try here. If she has normal hair, but doesn't look like these pictures, try here. And if your doll involves loads of pink and yellow hair and earrings that don't flash (or their holes) this is where you need to go.
Enjoy!!