Exodus 28:9–11
9 You shall take two onyx stones, and engrave on them the names of the sons of Israel, 10 six of their names on the one stone, and the names of the remaining six on the other stone, in the order of their birth. 11 As a jeweler engraves signets, so shall you engrave the two stones with the names of the sons of Israel. You shall enclose them in settings of gold filigree.
Exodus 28:21
21 There shall be twelve stones with their names according to the names of the sons of Israel. They shall be like signets, each engraved with its name, for the twelve tribes.