Breastpiece

A pouch worn on the chest of the high priest.

The breastpiece was worn by the high priest

Leviticus 8:5–9 See also Exodus 28:15–16, Exodus 28:29, Exodus 39:8–9

And Moses said to them, “This is what the LORD has commanded to be done.” Then Moses presented Aaron and his sons and washed them with water. He put the tunic on Aaron, tied the sash around him, clothed him with the robe, and put the ephod on him. He tied the woven band of the ephod around him and fastened it to him. Then he put the breastpiece on him and placed the Urim and Thummim in the breastpiece. Moses also put the turban on Aaron’s head and set the gold plate, the holy diadem, on the front of the turban, as the LORD had commanded him.

It was adorned with twelve precious stones

Exodus 28:17–21 See also Exodus 25:3–7, Exodus 39:10–14

And mount on it a setting of gemstones, four rows of stones: In the first row there shall be a ruby, a topaz, and an emerald; in the second row a turquoise, a sapphire, and a diamond; in the third row a jacinth, an agate, and an amethyst; and in the fourth row a beryl, an onyx, and a jasper. Mount these stones in gold filigree settings. The twelve stones are to correspond to the names of the sons of Israel, each engraved like a seal with the name of one of the twelve tribes.

It contained the Urim and Thummim

Exodus 28:30 The Urim and Thummim were used in decision-making. See also Leviticus 8:8

And place the Urim and Thummim in the breastpiece of judgment, so that they will also be over Aaron’s heart whenever he comes before the LORD. Aaron will continually carry the judgment of the sons of Israel over his heart before the LORD.

It was attached to the ephod

Exodus 28:22–28 See also Exodus 39:15–21

For the breastpiece, make braided chains like cords of pure gold. You are also to make two gold rings and fasten them to the two corners of the breastpiece. Then fasten the two gold chains to the two gold rings at the corners of the breastpiece, and fasten the other ends of the two chains to the two filigree settings, attaching them to the shoulder pieces of the ephod at the front. Make two more gold rings and attach them to the other two corners of the breastpiece, on the inside edge next to the ephod. Make two additional gold rings and attach them to the bottom of the two shoulder pieces of the ephod, on its front, near its seam just above its woven waistband. The rings of the breastpiece shall be tied to the rings of the ephod with a cord of blue yarn, so that the breastpiece is above the waistband of the ephod and does not swing out from the ephod.