Exodus 39:7-9

21st Century 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 skillful work, like the work of the ephod: of gold, blue and purple and scarlet, and finetwined linen.

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