The twelve stones are to correspond to the names of the sons of Israel, each engraved like a seal with the name of one of the twelve tribes.
KJV
And the stones shall be with the names of the children of Israel, twelve, according to their names, [like] the engravings of a signet; every one with his name shall they be according to the twelve tribes.
ASV
And the stones shall be according to the names of the children of Israel, twelve, according to their names; like the engravings of a signet, every one according to his name, they shall be for the twelve tribes.