Challenge description: "Create a photo in which your main light source is also your main subject."
I'm not believing that that ring is providing the light for this image. If it is, I'm sorry... but DNMC, in my opinion. The subject has to be the light source, too.
It's a nice photo, but the assignment said: 'Create a photo in which your main light source is also your main subject' and I don't see your main light source in this photo. Can't be the ring as a ring itself gives no light.