Jasper is a precious green stone, resembling emerald in appearance. It recalls the patina on a shield, from which it received its name.
Carnelian is another precious stone, fiery in brilliance and blood-red in hue.
Thus jasper signifies for us that God gives life and provides for all.
For all nourishment for men, and also for four-footed creatures, birds, and creeping things, begins and comes from green growth.
The prophet says: "You cause grass to grow for cattle, and green plants for the service of man, to bring forth food from the earth.
And wine that gladdens the heart of man, and oil that makes his face shine" (Ps 103:14-15).
Again, at the creation of the world the Lord said: "Let the earth bring forth green plants, grass bearing seed according to its kind" (Gen 1:11).
This, then, is what the jasper reveals.
Carnelian depicts the dreadfulness of God. Moses, who saw God, says: "The Lord your God is a consuming fire" (Deut 4:24).
The prophet also cries to Him: "You are terrible, and who can stand before Your face?" (Ps 75:8).
In agreement with him, the wise Apostle writes: "It is a fearful thing to fall into the hands of the living God" (Heb 10:31).
Truly, the blameless goodness of God is unacceptable to lovers of sin and to the proud in spirit.
It does not bring them to repentance, but gives them the freedom to fall into error.
Thus it is quite fitting that, together with goodness and benefactions, dreadfulness should also be depicted in God.
But carnelian does not hold first place with God. In describing Him, jasper must certainly come first.
For His nature is self-existing goodness, love for mankind, and providential care. He wishes to be our Father more than our Master.
Yet we, if one may say so, compel Him to dreadfulness and punishments.
Often, setting aside the compassion proper to His nature, He acts in a way contrary to His nature by showing severity.
The reference is evidently to a copper shield, which as it oxidizes seems to grow over with a green patina.