Opal Play-of-Color translates the diffraction physics of Australian black opal into an interface language. Stacked silica microspheres split light into shifting patches of cyan, green, pink and gold, all glowing against the near-black ironstone potch that cradles the stone. Green-teal leads — the most common flash — while electric blue, magenta, violet and a rare gold-orange surface as the eye moves. The result is luminous, gem-faceted and dark, never garish: subtle spectral shimmer rather than rainbow noise.