Saw this when I was pretty young- maybe late 70's or early 80's? Anyway, there's a doll and she's under a glass dome but at one point in the movie, she falls to the ground and "magic dust" comes out of her head? Sorry, that's about all I remember but it's been driving me and my sister crazy all these years!

Child of Glass (http://www.imdb.com/title/tt0077325/)?

That was the movie that was suggested on another site but after checking out some of the clips, I don't think it's the movie I'm looking for. I distinctly recall a porcelain doll with blond hair and under a glass dome. In Chid of Glass, the doll has brown hair, not under a dome, and no "sparkly dust" coming out of her head- just diamonds spilling out to the ground. Thanks anyway!