What did Miss Minchin accused Becky for?

In Frances Hodgson Burnett's novel The Little Princess, Miss Minchin, the boarding school principal, accuses Becky, the school maid, of stealing Miss Minchin's sister, Miss Amelia's jewellery. Miss Minchin believed that Becky had taken her jewelry from Miss Amelia's room and despite having no evidence to support her claim, she accused her of theft. Becky is punished and kicked out of school, but she later loses her jewelry and it is revealed that Becky is innocent of her crimes.