What makes mood rings change color?

i got a mood ring today and want to know how it changes its color. i know it has to do with body temperature, but thats it...What makes mood rings change color?
';Liquid Crystal'; is the key ingredient in all types of ';Mood Jewelry'; that does the color-changing.What makes mood rings change color?
It's the heat in your hand.

Put it in the freezer and it'll change colors. Probably black.
yep its to do with heat

its called ';thermochromism';



http://en.wikipedia.org/wiki/Thermochrom