Hi Katy,
I hope you will come here more often
I went through the same thing with my daughter, just she was saying she wants to be white like mommy. We live in a white country (only a small percentage of others) so i guess thats why she felt its better to be white, its better to be like others. I know it was mainly cos of kids in the kindergarten, one day she came back home and start saying - this is white (pointing at my hand) and this is black (pointing at her hand) i was shocked! I told her no one is white, even me. I took a piece of paper near my hand and asked her if thats the same color as my hand? she said no, and i asked what color has that paper - she said white - so i said - see? i am not white

i said its just the way people describe the shade of the skin, but its not always accurate. And i said that people have different shades of skin color, and none is better than others. It would be boring if we would all look the same. And i said i can get similar skin color to hers when i will get the sun tan and that many people wants to be tanned so its all good.
In your case its kinda reversed. But you could still point out that different people have different shades of skin. Like even black people are not the same - you can find so many shades of their skins, same with whites. So there is no need to be exactly the same as others. And i think its not early to talk about it, beacuse she already sees the difference.
I know its not easy, for me it was a very hard time. So good luck