The answer is: Blue

Exo 28:31 - the middle garment, beneath the ephod and above the coat, made from one piece of fabric and similar in design to the robe Christ was wearing at the crucifixon (John 19:23)

The blue color of the priest's robe plays a significant role in the symbolism of holiness and divine service. In ancient Israel, blue was often associated with the sky and the heavens, reflecting a connection to the divine. A fascinating fact about this color is that in the days of the Israelites, dyeing fabric blue was an important and costly process, sometimes utilizing a special type of shellfish known as murex. This made blue robes not only a symbol of God’s special calling but also a sign of prestige and distinction.

The similarities between the priest’s robe and the garment of Christ at the crucifixion connected ancient practices with central themes of sacrifice and redemption found in Christianity. In John 19:23, the seamless robe that the soldiers cast lots for speaks to the idea of unity and integrity in God's creation.

Furthermore, the priest's attire, including the blue robe, was commanded by God as part of an elaborate system intended to demonstrate how sacred and distinct the role of a priest was, set apart for serving the community in worship, mediation, and ritual. The continuation of these color traditions can even be seen today in various religious garments — the vibrant blue can still represent spirituality and devotion.

So next time you think of the pivotal events in both the Old and New Testaments, remember how symbolism and color stitched an enduring tapestry of faith across history!