Like unto preserved pearls,indicating that they are just as white and pure fresh pearls.We mentioned Allah's statement,كَأَنَّهُنَّ بَيْضٌ مَّكْنُونٌ As if they were eggs preserved. (37:49), in Surah As-Saffat, and also their description in Surah Ar-Rahman.This is why Allah said afterwards,جَزَاء بِمَا كَانُوا يَعْمَلُونَ