"You are to make a plate of pure gold and engrave it, like the engraving of a seal: HOLY TO THE LORD
References for Exodus 28:36
Fasten it to a cord of blue yarn so it can be placed on the turban; the plate is to be on the front of the turban.
It will be on Aaron's forehead so that Aaron may bear the guilt connected with the holy offerings that the Israelites consecrate as all their holy gifts. It is always to be on his forehead, so that they may find acceptance with the Lord.