This is really simple and pretty. However, the lighting is washing out the portrait, and reflecting too much on the metal which exaggerates the soft focus. The detail on it is beautiful - I don't think it needs a soft focus.
I think (and I don't count) that if you had done this in color it would have popped more...and your focus should have been a little lower to have the whole cameo in focus...not the chain and the top of the cameo...but a good shot otherwise
Cameo's are beautiful. I love the form of the girl, how she's in contrast with the rest of the picture [including the background]. The bottom of the necklace looks out of focus, but overall a good photo.