Problem: Mark and John refer to Jesus’ robe as “purple” (Jn. 19:2; Mk. 15:17), while Matthew refers to it as “scarlet” (Mt. 27:28). Luke doesn’t mention the color, merely calling it a “gorgeous robe” (Lk. 23:11). Which color was Jesus’ robe?
Solution: A couple of responses are plausible:
First, ancient people didn’t easily distinguish or classify colors as we do today. After all, color charts did not exist in the ancient world, and therefore, identifying colors was subjective to some degree. Even today, people differ over whether or not a shirt is “dark purple” or “maroon.” Since scarlet and purple are so similar to one another, one witness could claim that the robe looked red, while the other could easily claim that it looked maroon or purple. It’s important to note that the gospel authors do not claim that the colors were radically different (i.e. blue versus yellow). Instead, they both describe a red-purple color.
Second, it’s possible that the robe contained two separate colors. This may sound like an ad hoc theory. However, after his scourging, Jesus was surely bleeding through the robe, which could have made it red in certain parts, rather than purple. Moreover, in Revelation, John describes the symbolic woman of Babylon as being clothed in both “purple and scarlet” (Rev. 17:4). Perhaps something similar was happening here.
 Morris writes, “The ancients do not seem to have distinguished very sharply between colors, at least in their nomenclature.” See footnote. Morris, L. (1995). The Gospel according to John (p. 700). Grand Rapids, MI: Wm. B. Eerdmans Publishing Co. Likewise, Carson writes, “The ancients did not discriminate among colors as closely as we do.” Carson, D. A. (1984). Matthew. In F. E. Gaebelein (Ed.), The Expositor’s Bible Commentary: Matthew, Mark, Luke (Vol. 8, p. 573). Grand Rapids, MI: Zondervan Publishing House.
“And they stripped him, and put on him a scarlet robe. (Matt 27:28)”