Matthew Poole and continuators on John 19:2

2 And the souldiers platted a crown of thorns, and put it on his head, and they put on him a purple robe .

The other Evangelists also mention a reed put into his right hand; the Crown, and the Purple Robe, and a Scepter, are all regal Ensigns, they give them to Christ in derision of his pretence to a Kingdom, and in the mean time themselves proclaim what he had said, That his Kingdom was not of this World; for tho earthly Kings wear Crowns, yet they use to be of Gold, not of Thorns; and their Scepters use to be Gold, not Reeds.