Well, since she's a very bright sky blue, I should think Cerulean would be the most appropriate.
Teal, Turquoise, Aquamarine, or any other overused synonym in the blue spectrum would go. But given how overused Cerulean is in bad fanfic, I opt for that. It would offset her flowing golden hair so nicely, too.
And she is Pallando's sister. Also, this allows the potential for confusion as to whether or not she is one of the two Blue Wizards who disappeared and Do Not Come Into These Stories. (As a matter of fact, I seem to recall at least one piece of lousy fanfic in which one of the two Blue Wizards was declared to have been a woman, who of course came back to rescue the Fellowship, or to defeat Sauron in the Fourth Age because the company had actually somehow botched the job and didn't really defeat him completed. Ack.)