Genesis 37:3
…and he made him a coat of many colours. Although Moses did not tell us so, I am certain that this garment was not simply a coat, but a mantle like Elijah’s, a badge of office and an emblem of divinely delegated authority. I am also certain that it was made in exactly twelve colors, one for each of the tribes of Israel over which Joseph would be given authority. Recall that the High Priest’s breastplate, as well as the foundations and the gates of the New Jerusalem, contained twelve precious stones of twelve different colors explicitly representing the twelve tribes. It was an independent confirmation of the prophecy which Joseph was soon to receive in a dream.