Was the robe put on Jesus scarlet or purple?

Matthew says what the garment was; Mark and John say what it was meant to be. Matthew calls it a chlamys kokkinē (Matthew 27:28). The chlamys was the short cloak worn by soldiers and officers, and kokkinos means scarlet, the colour of the crimson dye made from the kermes insect. A soldier’s red cloak was just the kind of thing to hand in the governor’s barracks. Mark and John call it purple (porphyra in Mark, porphyrous in John), the colour of royal robes, because the point of the mockery was to dress Jesus up as a king, with a crown of thorns and a reed for a sceptre, and hail him as “King of the Jews”.

Ancient colour words were not as exact as ours. ‘Purple’ covered a range of shades from crimson to violet, depending on the dye, and a faded scarlet cloak could fairly be called either. Barnes notes that ‘the ancients gave the name purple to any color that had a mixture of red in it’. So the soldiers threw a red military cloak on Jesus as a mock royal purple, and the Gospel writers describe the same garment in the terms that suited their accounts.