'Stone' in the Bible

You show that you are a letter from Christ, delivered by us, written not with ink but with the Spirit of the living God, not on tablets of stone but on tablets of human hearts.

Now if the ministry of death, engraved in letters on stones [the covenant of the Law which led to death because of sin], came with such glory and splendor that the Israelites were not able to look steadily at the face of Moses because of its glory, [a brilliance] that was fading,