The Necklace of Princess Fiorimonde by Mary de Morgan

Once there lived a King, whose wife was dead, but who had a most beautiful daughter -- so beautiful that everyone thought she must be good as well, instead of which the Princess was really very wicked, and practised witchcraft and black magic, which she had learned from an old witch who lived in a hut on the side of a lonely mountain. This old witch was wicked and hideous, and no one but the King's daughter knew that she lived there; but at night, when everyone else was asleep, the Princess, whose name was Fiorimonde, used to visit her by stealth to learn sorcery. It was only the witch's arts which had made Fiorimonde so beautiful that there was no one like her in the world, and in return the Princess helped her with all her tricks, and never told anyone she was there.

The time came when the King began to think he should like his daughter to marry, so he summoned his council and said, "We have no son to reign after our death, so we had best seek for a suitable prince to marry to our royal daughter, and then, when we are too old, he shall be king in our stead. " And all the council said he was very wise, and it would be well for the Princess to marry. So heralds were sent to all the neighbouring kings and princes to say that the King would choose a husband for the Princess, who should be king after him. But when Fiorimonde heard this she wept with rage, for she knew quite well that if she had a husband he would find out how she went to visit the old witch, and would stop her practising magic, and then she would lose her beauty.