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?

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!