There's nothing more dangerous than a nobody who threatens your sexy way of life by being sexy without flaunting it. Now's your time to be her shepherd.
Tell her the science hasn't been created yet. Then, when the time is right...give her the gift of sight.
I repeat: Do not let her brush her hair all by herself. First it's brushing her own hair, then what's next? Getting bangs without your permission??
This will foster a codependency that will ensure that she doesn't feel pretty until you say so.
She'll be whiny and whimpery for a few days -- that's to be expected. Do not speak to her until the redness has gone down.