I managed to do some more careful analysis. I found a hi-res photo of the shield on a poster. Given that there are many fan posters out there, I feel this is an authentic wallpaper.
Bear in mind that photos of shields -- or any prop -- must take into account camera distance and angle. Too close and there will be a fish-eye like distortion. Differences in angle and perspective will be very noticeable with concentric circles.
Also, we have to ascertain if the image we're seeing is an elaborate computer 3D model or not - and if so, if the prop is identical to the computer model. If it's a computer model, chances of tilt and perspective angles being off are possibly reduced.
So here is my overlay analysis of the poster. I brightened it up as much as I can and traced concentric circles over the lines I see.
Looks like this shield image may not suffer from any perspective distortion.
Now when we take Valor's image of the 10" and place it under my tracing:
Notice that the outer red track of the shield in Valor's pic is narrower than the inner red track, so I don't know if that's by design or by virtue of the camera being a bit close. I was also having a hard time getting a precise overlay of just the inside star and smaller concentric circles, so there the camera may have been at a slight angle.
Anyways, this looks like a fairly decent nod to the 10"+/- blue circle and star size.
Thoughts?
BTW, if anyone wants my computer file and wouldn't mind making a shield for me at one point (I'll pay, of course), I'd be more than happy to do any additional analysis if I'm able.