Exodus 28:15

28:15 “You are to make a breastpiece for use in making decisions, the work of an artistic designer; you are to make it in the same fashion as the ephod; you are to make it of gold, blue, purple, scarlet, and fine twisted linen.

Exodus 28:30

28:30 “You are to put the Urim and the Thummim into the breastpiece of decision; and they are to be over Aaron’s heart when he goes in before the Lord. Aaron is to bear the decisions of the Israelites over his heart before the Lord continually.