Beautifully lit, and I like your selective desaturation. I can some random pink streaks here and there on her skin -- face and shoulder especially. It's hard to tell with the mask, but my first impression is that the model isn't trilled to be posing. :-}
i like this picture alot... my only suggestion if you try this again is that this particular mask is so vibrant, so it seems that putting a sad face behind it takes away the effect... if she was laughing or smiling i think it would bring it all together a little better... im not a pro photographer or anything, i just know theatre haha beautiful pic tho