So I saw this movie in France when I was a kid, but hopefully someone saw it. I remember a girl being lured to a well by her sister or friend (not too sure) and there is a necklace there. Her sister pushes her in the well and she falls in. She is transported into another world? She returns later for the prince/love interest.

This has been a long search... hopefully you can help

Once Upon a Time (1976) (http://www.imdb.com/title/tt0075011/)