3x3+1 Spheres

I put this scene together as a random test for my depth of field code (hadn't tested it yet), and it turned out a lot more interesting that I had thought. Even more so for a test.

Nine spheres in a 3x3 matrix resting on a world sized sphere. The small ones are refractive and the three furthest from the camera contain a primary colour light source each (no other light sources in the scene).