Idly putting this out there: there's a school of thought that notes that Cleopatra VII Philopator (yes, that Cleopatra) wasn't typically described in contemporary sources as attractive. She was charismatic, she had a forceful personality and a sense of humor, and she was - kind of unusually for later Ptolemies - relatively well-educated, but her physical beauty never really came up. 
🇳🇱
@noelle Serious scholarly response though:
There is really only one historic quote about Cleopatra regarding her beauty as far as I know. This comes from Plutarch:
"For her beauty, as we are told, was in itself not altogether incomparable, nor such as to strike those who saw her; but converse with her had an irresistible charm, and her presence, combined with the persuasiveness of her discourse and the character which was somehow diffused about her behaviour towards others, had something stimulating about it. There was sweetness also in the tones of her voice; and her tongue, like an instrument of many strings, she could readily turn to whatever language she pleased..."
Which implies what you said. She was not a great beauty but she was quite charming.
@noelle Another related quote by Plutarch that is earlier in the same text (Life of Antony, XXV.3):
"Judging by the proofs which she had had before this of the effect of her beauty upon Caius Caesar and Gnaeus the son of Pompey, she had hopes that she would more easily bring Antony to her feet. For Caesar and Pompey had known her when she was still a girl and inexperienced in affairs, but she was going to visit Antony at the very time when women have the most brilliant beauty and are at the acme of intellectual power"
@noelle And not to drag this out, but attached are some busts of Cleopatra that likely gives a fairly honest representation of her beauty.