I'm guessing that this person only knows of basic run-of-the-mill white cultured freshwater pearls. Which means she apparently is ignorant as hell to the fact that pearls can and do naturally come in a rainbow of colors.

Like Tahitian pearls, which are fucking awesome and gorgeous. Seriously, Google-image search for them if you don't know what I'm talking about. Such pretty little gems! They make traditional white pearls look positively boring!

(Honestly, if the dominant, dark-skinned race is called "coal" why isn't the oppressed, light-skinned race called "chalk"?)