Exodus 39:7-9

King James Version

⁷ And he put them on the shoulders of the ephod, that they should be stones for a memorial to the children of Israel; as the Lord commanded Moses.

⁸ And he made the breastplate of cunning work, like the work of the ephod; of gold, blue, and purple, and scarlet, and fine twined linen.

⁹ It was foursquare; they made the breastplate double: a span was the length thereof, and a span the breadth thereof, being doubled.