Sorry, I realize not all gifts from rulers are the equivalent of party favors. In this case, if those were natural Golden south sea pearls they would be extremely valuable. Also, the swirl mark on the center pearl only happens on cultured pearls. If the line went all the way around, it would be a circle pearl. So far, I have never seen a natural pearl with circle marks. So in my opinion this strand has the marks of a royal party favor- nice, but flawed, gems. It is low end for South Sea pearls if it has that mark on the largest pearl. I was not awarded my party favor at a dinner, where they usually show up, but in the shaik's throne room. It is considered a token of esteem. It was still party favor quality for a rich royalty to give away. I will apologize profusely if this strand is not a lowish end cultured SS, probably from somewhere in French Polynesia. What gives it its great provenance is the story, esp, if you collect some evidence like a fee for drilling, or a photo of them undrilled or your aunt wearing them, or of the princess in question with or without your aunt.
And, you should enjoy wearing them- they are South Sea pearls, after all!