9 And thou shalt take two onyx stones, and grave on them the names of the children of Israel:

10 Six of their names on one stone, and the other six names of the rest on the other stone, according to their birth.

11 With the work of an engraver in stone, like the engravings of a signet, shalt thou engrave the two stones with the names of the children of Israel: thou shalt make them to be set in ouches of gold.

12 And thou shalt put the two stones upon the shoulders of the ephod for stones of memorial unto the children of Israel: and Aaron shall bear their names before the Lord upon his two shoulders for a memorial.

On each shoulder of the priests would be an onyx stone, each set in a golden base and each with half of the tribes of Israel engraved on its face. According to Josephus, the names were written in order of birth, the six elder sons of Jacob being placed upon the right shoulder, and the six younger upon the left.

Thus, the priests literally bore the weight of the twelve tribes upon their shoulders, a constant reminder that they stood not only representatives of God, but also of all the people. Every move of the arm and hands while carrying out of their tabernacle duties would shift the tribes upon their shoulders.

God also specifies that the stones were to be engraved “like the engravings of a signet.” A signet was a ring or a bracelet with a person’s name carved into it, which would be pressed into wax as a seal or signature for whatever document it was attached to. There is no record of the shoulder stones ever being used literally as a signet, but God does seem to be suggesting that they are to be viewed as a sort of signature of the people upon the priests.