The ring will change color according to the temperature of your body. Can a ring really tell you what mood you are in? I would think it can't, but some think it can.
What the Mood Ring Colors Mean:
The top of the list is the warmest temperature, at violet, moving to the coolest temperature, at black.
violet blue - happy, romantic
blue - calm, relaxed
green - average, not much going on with you
yellow/amber - tense, excited
brown/gray - nervous, anxious
black - cold temperature or damaged ring