Well, this is the best on curtains I could come up with on a short notice. If you put a differently coloured tex in Trnasparency, you'll get a darker material. If you put the bead into zero postion on Transparent, the material will be too light if the colour is white and too dark if it's black. You can experiment. Increased refraction darkens the material. Yes, you can see there's a figure behind the curtain, but further experimentation with values of gray in Transparency might yield better results. Of course, the darker the more transparent.

-- erlik