Mishnà su Levitico 13:1

The signs of negaim are two which, in fact, are four. The bright spot (baheret) is bright white like snow; secondary to it is the sign as white as the lime of the Temple. The rising (se'et) is as white of the skin of an egg; secondary to it is the like white wool, the words of Rabbi Meir. But the sages say: the rising (se'et) is white wool and secondary to it is like the white of the skin of an egg.