Lightbox testing

On a whim I clipped together a couple of sheets of paper (actually some bills that I had lying around) and fashioned a sort of lightbox out of them... see the setup shot. I then photographed this Yule ornament, which turned out okay once I got the settings right. I even got that seamless white background look almost totally in-camera, and with only one light... I removed a bit of visible seam from one corner.

As you can see in the setup shot, it was just the one SB-600 pointed down from above, through a sheet of paper. The only thing bothering me here is the reflection of the hole in the box, the one I'm shooting through. The transition from specular highlight to dark is just too abrupt. Any ideas on how I could've gotten rid of that, given this highly reflective object, would be appreciated...