Saw this online awhile back. Pretty neat and very presentable. However, its not cheap. Anyway, they claim they have the giants of watchmaking like Mr Dufour using their loupes. Check out their website.
Link : http://www.loupesystem.com
The best part is, you don't need to be a professional or a DSLR to use this. Just pop it onto your iPhone and fire away. Plus points for the convenience.