Iridized frit images are currently being updated. Uroboros' FX90 Iridized Frit is unique to the industry and adds rich, reflective, color highlights and complexity to glass work. Rainbow irid coating is available on Clear and black. The strongest visual effect occurs with the black, or with transparent colors over darker background colors. Only our three larger sizes, F3, F5 & F7 are produced with Iridescence because the visual effect is diminished on smaller particle sizes.