When, on one occasion, my confessor told me to ask the Lord Jesus the meaning of the two rays in the image, I answered, "Very well, I will ask the Lord."
During prayer I heard these words within me: The two rays denote Blood and Water. The pale ray stands for the Water which makes souls righteous. The read ray stands for the Blood which is the life of souls . . .
These two rays issued forth from the very depths of My tender mercy when my agonized Heart was opened by a lance on the Cross.
These rays shield souls from the wrath of My Father. Happy is the one who will dwell in their shelter, for the just hand of God shall not lay hold of him. I desire that the first Sunday after Easter be the Feast of Mercy. (299)
From: Diary of St. Faustina: Divine Mercy in My Soul