The breastpiece (see Exodus 28:15–30) was made it from embroidered linen folded in half. It had twelve stones, each engraved with the name of an Israelite tribe. A gold chain from the gold shoulder pieces of the ephod held it over the chest.
The priests placed the Urim and Thummim in the breastpiece pocket (Exodus 28:30; 1 Samuel 23:9–12; 30:7–8). Their exact purpose is unclear. Most scholars think they are two stones, possibly different in color, that were cast as lots. They could give a positive, neutral, or negative answer to difficult questions (Exodus 28:30; Numbers 27:21; 1 Samuel 28:6). Their mention in later Old Testament prophetic writings shows how important these items were for the work of the priest (Ezra 2:63; Nehemiah 7:65).