Rings - I used two rings in my example, each one on a separate layer; a dark blue and light blue one.
I slightly shifted one layer (that I turned into a clipping layer first) to get the 3D effect.
Halo - I merged the two layers, added a slight inner shadow, made a copy and blurred it a few times.
I used a mask on this blurred layer to remove the blur on the ring itself, closest to the viewer.
Shadow - The shadow is created by another copy of the ring, filled with black, stretched, blurred and a mask with alinear b/w gradient was added to make the shadow softer on one side.
Finsihing touch - I added a background, merged all layers, copied the result to a new layer and sharpened it. Then I added a mask to this layer and with a soft black brush I painted on the mask to remove some sharpness from the background.
I don't know if this is what you want, since you mentioned something about a 3D (?) halo,
but maybe it helps you to come up with some ideas of your own.
Don't try to follow the exact steps in my example, it's just to give you some global idea, since I left out several tricks that would make this a huge tutorial and that's not what I had in mind.
3D halo 
Linear Mode
