Diadem in Fausset's Bible Dictionary

(See CROWN.) The diadem in Gentile nations was a white fillet, two inches broad, bound round the head, the badge of the monarch. In Persia the king's diadem differed from that of the queen and the highest princes, in having an erect triangular peak. In Israel mitsenepheth is always the high priest's turbaned cap, "miter," or "diadem," (Isaiah 28:5) "diadem (tsephirah) of beauty."