Okay, so I'm not the best at explaining this but I'll give it a go as google came up with nothing 
This film was either filmed in the 80's or early 90's. I was very young when I saw it but there was this magic red necklace and two worlds I think, and a boy and girl had to try and find and return this necklace to the other world where this woman (I don't know the species) needed it (she was good). If you said the word 'wish', you could make anyone do anything. At one point, a girl gets hold of it and uses it to go shopping by saying things like 'oh I really wish you'd let me have all this' so that she could get the stuff.
If anyone could identify this film, I'd be most obliged!!