Could you please post an image of this actor as well as an image of a Sikh that you consider the proper color for a Sikh? Please.
I'm not good with images, but Benedict Cumberpatch has images all over.
I don't know that there is "the" proper color (natives of India do have variety in their skin hues), but someone of descent from the Indian sub-continent would have been a good start.
I put the spoiler in white in case people didn't want to see a spoiler before the movie even came out.