Exodus 28:16-17

28:16 It is to be square when doubled, nine inches long and nine inches wide. 28:17 You are to set in it a setting for stones, four rows of stones, a row with a ruby, a topaz, and a beryl – the first row;

Exodus 28:21

28:21 The stones are to be for the names of the sons of Israel, twelve, according to the number of their names. Each name according to the twelve tribes is to be like the engravings of a seal.