Here's a thought that I haven't tried, but one thing you could do is setting all the figure's materials to maximum (white or blue) ambience, rendering and saving, then pushing the camera forward or back slightly and changing the camera focal length, delete or hide the figure and re-render. This will give you two images which you should be able to composite together in a paint program, using the 'ambient' figure as an alpha channel. The slight difference in camera position and field of view in the second image, which replaces the figure in the first should give you some illusion of refraction! Watch out for anti-aliasing around the figure edges!