First off a quick look at the originals in the Crimea. I think you would be hard pressed to see what colour the turban is from this very early photograph. However I think it is fair to say that it does not stand out from the fez in a particularly striking way.
Taking the widespread advice to lighten the shade of green I took up a fairly bright shade, put it on the turban and to my mind it is an instant improvement. The striking thing is that a shade which is far too bright and sickly shade works in the context of scale and surrounding colours.