Exodus 28:9-12

“Take two onyx stones, and engrave on them the names of the tribes of Israel. Six names will be on each stone, arranged in the order of the births of the original sons of Israel. 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.