Struan;

Many years ago, an early photographer made a color photo by placing a silver halide glass plate in contact with a pool of mercury which then set up diffraction rings in the coating. By proper illumination, the developed image was able to reproduce the original colors. I am not sure I remember who did it, my memory is faulty on this one, but they reportedly have one at George Eastman House but cannot diiplay or recreate it due to the use of an open pool of mercury. However, I think it should be possible to do by other means.

PE