Exodus 28:13

With the work of an engraver in stone, like the engravings of a signet, you shall engrave the two stones, according to the names of the children of Israel: you shall make them to be enclosed in settings of gold.

You shall put the two stones on the shoulder straps of the ephod, to be stones of memorial for the children of Israel: and Aaron shall bear their names before Yahweh on his two shoulders for a memorial.

and two chains of pure gold; you shall make them like cords of braided work: and you shall put the braided chains on the settings.

You shall make a breastplate of judgment, the work of the skillful workman; like the work of the ephod you shall make it; of gold, of blue, and purple, and scarlet, and fine twined linen, you shall make it.