The existence of the souls starts to become manifest in the world of Beria. For this reason, the vessels of the ten sefirot, which measure the amount and portion for the souls in actual reality, are necessarily not Divinity but are newly formed, as there is no possibility of any changes or numbers in Divinity. Accordingly, we attribute three hues to the ten sefirot in Beria, Yetzira, and Asiya: Red, green, and black, so that it is impossible to even imagine that they have an aspect of Divinity, as nothing newly formed applies to Him, God forbid.
Ten Sefirot of Beria as Newly Formed Emanations
Baal HaSulam's Preface to Zohar 27:2