I'd be looking for more focus and detail in this image. It looks slightly cloudy. Nice idea though. Don't change the dark background. That works, except where the object it's resting on shows. Good luck with the challenge.
I like what you were trying to do here. The focus seems just a bit too soft to me, which gives the white light in the center more power than it otherwise should have. Cropping on the sides could have been a touch tighter, but this is an excellent example of backlighting.