Well there is no way to "theorise" her skin colour, at least not with any level of accuracy.

Sure Macedonians were Caucasian, but some were fairer and light-haired while others were swarthier and dark haired. Maybe she took after golden haired Ptolemy II through the paternal line or maybe she took after some of the Persian, Anatolian and Sogdian ancestors through her maternal line.

Some scholars like Dr. Duane Roller have suggested that her mother was an Egyptian but I respectfully do not believe there is enough evidence to speculate as to the scope of her ancestry with any certainty beyond the obvious conclusion that most of her ancestors were Macedonian or Greek and a few others were Near Easterners and Central Asian.

She definitely was not black like some Africentrists would claim but unlike many others claim on the internet there are no ancient accounts describing her as a strawberry blonde. The thing is, ancient authors have a lot to say about Cleopatra but nothing in the way of a physical description besides vague references to the fact that she was charming and somewhat attractive. The closest thing I can find to an ancient description of her is a passage in Lucan's Pharsalia which describes her as fair breasted but although elements of this poem are believed to be based on historical accounts it is still fictionalised and poetic, being written about a century after she died.

On the one hand, Southern Europeans living around the Mediterranean have a stronger tendency towards tan or olive skin than those in more northern areas. On the other hand, as an aristocratic woman she would have spent more time indoors than her male counterparts and have been somewhat more secluded from the sun's rays.

But as for theories on her skin colour? She probably looked Greco-Macedonian, it just so happens that not all Greco-Macedonians looked the same.

Thanks for such a detailed answer.