Jamieson, Fausset and Brown on Exodus 28:31-33

31-33. the robe of the ephod all of blue--It was the middle garment, under the ephod and above the coat. It had a hole through which the head was thrust, and was formed carefully of one piece, such as was the robe of Christ (Joh 19:23). The high priest's was of a sky-blue color. The binding at the neck was strongly woven, and it terminated below in a fringe, made of blue, purple, and scarlet tassels, in the form of a pomegranate, interspersed with small bells of gold, which tinkled as the wearer was in motion.