By suppressing the diffuse ultraviolet reflectance, the directionality and spectral purity of the iridescence is heightened.
baɪ səpɹˈɛsɪŋ ðə dᵻfjˈuːz ˌʊltɹɐvˈaɪəlɪt ɹᵻflˈɛktəns, ðə dᵻɹˌɛkʃənˈælᵻɾi ænd spˈɛktɹəl pjˈʊɹɹᵻɾi ʌvðɪ ˌɪɹɪdˈɛsəns ɪz hˈaɪʔn̩d.