EXO 28:21

21 And the avanim [(gemstones)] shall be for the Shemot Bnei Yisroel, Shteym Esreh [(Twelve)], according to their Shemot, like the engravings of a chotam [(signet ring)]; every one with shmo shall they be according to the Shnei Asar Shevet [(Twelve Tribes)].