I have worn mine in the shower and swimming and it still works Granted it doesnt look as good or work as fast as it did before it got wet.
you can get a mood ring anywhere really...but you have to be careful and not get a piece of shit one cause they wont really work or last as long...
it's best to keep it from water and extreme temperatures.... I've had a mood ring that stoped working once wet
Oh, well i just bought a cheap one and it still 'works' even though i wash my hands with it on and stuff! sometimes they break though.