Question: Near the end of the movie, the grand duke calls the footman to bring him the glass slipper, so he can try it on Cinderella. But Lady Tremaine trips the footman, causing the slipper to fly and shatter. Then Cinderella reveals she has the other slipper. The grand duke tries it on her, and find that it fits. I have a problem with that because how did he know the glass slipper Cinderella had was the same size as the one that broke?
Answer: Add in that how many possible glass slippers could there possibly be? It would be an incredibly uncommon type of shoe that would be amazingly difficult to make.
Answer: Probably because it looked the same to him, and he had been handling it a lot for all the trying-ons, plus how many people have glass slippers in their closet? But you are right it heavily suggests she is the person, not proves it. But then again how many women's feet would it have already fit? He should have found many matches long before getting to Cinderella. Cinderella can't be the only woman in the kingdom with her size foot.
Answer: Cinderella's entire outfit was magically created by the Fairy Godmother. Not only was the spare shoe Cinderella had in her possession identical to the other one, it likely would be charmed so that she is the only one who can wear it. It's similar to young Arthur being the only person who could pull Excalibur from the stone because he was the true king. No other woman who attended the ball wore glass slippers. If they had, they'd be able to also produce the spare shoe as proof.
raywest ★