[I realized if you look again to the reference, you see Amethyst's mane look different when wearing a hat.
And this mare had a same mane style as Amethyst.](https://static.wikia.nocookie.net/mlp/images/f/fe/Princess_Ember_looking_over_at_Spike_S7E15.png/revision/latest?cb=20170820150350)

[So logically, her mane is the same as Amethyst as usual.](https://static.wikia.nocookie.net/mlp/images/f/fe/Princess_Ember_looking_over_at_Spike_S7E15.png/revision/latest?cb=20170820150350)