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 color blue holds significant meaning in biblical scriptures, beyond just the robes of priests. In Exodus 28:31, this particular hue symbolizes the heavenly and divine. The priests wore these garments as a representation of the connection between God and the people. Similarly, in the New Testament, Jesus’ robe at the crucifixion signifies his royal and priestly identity — a fascinating thread that binds both Old and New Testament narratives.

Additional trivia reveals that blue dye was not just common and easily accessible; it was luxurious and often costly, originating from the Murex snails found along the Mediterranean shores. This was a rare and precious resource, making the blue robes even more special and sacred.

The robe’s design, tailored to enhance the visual appeal of the priests during their righteous duties, draws parallels with God’s holistic approach to spirituality—merging functionality, beauty, and meaning. Just like the splendor of creation itself, these garments reflected the art and creativity alive in God’s service.

Moreover, when we think about colors in the Bible, some believe that the color blue relates to God's commandments. Its significance in religion and culture grows richer, enveloping traditions spanning centuries and numerous communities. From the blue fringes mentioned in Numbers 15:38 to the azure skies representing God’s expansive authority, blue remains an enchanting color of questing devotion. It's a reminder that authenticity and beauty in spirit go hand-in-hand.