My mood ring is black all the time?

i have a new mood ring, i use to have them as a little girl and they where alway bright colorfull colers but now i got one from hottopic and its always black or a dark blue. but when my frieands wear it the thing explodes into a colorfull chaos. what dose black and dark blue mean for a mood ring? black is my favorit color but i wanted a ring that is always a new color not the same old black. and i was curiouse to see how acurate. it seems acurtate on others but with me just black and dark blue. once it turned pink but besides that just those two colors