Exodus 28:11-12, 21

Engrave these names on the two stones in the same way a jeweler engraves a seal. Then mount the stones in settings of gold filigree. Fasten the two stones on the shoulder-pieces of the ephod as a reminder that Aaron represents the people of Israel. Aaron will carry these names on his shoulders as a constant reminder whenever he goes before the LORD.

Each stone will represent one of the twelve sons of Israel, and the name of that tribe will be engraved on it like a seal.