Rainbow quartz

Who among us does not enjoy the vision of a rainbow The spectral colors spread out across the sky inspire awe and pleasure no matter how many times we see them. For this reason, we have attempted to replicate rainbows artificially. We can go to any toyshop and find rainbow glasses, any rock shop and find rainbow quartz made by plasma ionization techniques. Jewelry and craft shops sell rainbow jewelry made by electroplating titanium or niobium oxide. Teachers use rainbow tubes with a universal indicator to demonstrate pH changes and acid-base reactions. Dye mixtures can be separated by rainbow electrophoresis and rainbow chromatography. Rainbow thermometers and toys are made from liquid crystals. Thermochromic materials can be heated to produce rainbow colors. Every toy shop is awash with rainbow colors, a phenomenon not available prior to the many inventions of the twentieth century [39]. 

M. R. Rainbow, S. Arterton, and R. C. Eberhardt, Fluorescence lifetime measurements using total internal reflection fluorimetry Evidence for a conformational change adsorbed to quartz, J. Biomed. Mater. Res. 21, 539-555 (1987). 

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