Rare chatoyant specimens will have a coarse silk with just the right spacing to serve as a diffraction grating. These specimens will produce not only a cat’s-eye, but also a display of spectral colors caused by light passing through the coarse silk and being diffracted into the colors of the spectrum. More familiar examples of diffraction are rainbows produced by sunlight diffracted by raindrops, or opal’s play-of-color caused by light diffracted by tiny spheres of opal within the gem.