These ultra-low cost beads are extremely sensitive to natural light and change colour dramatically from white to various colours when taken outside - even on an overcast day. Containing trace amounts of a photochromic pigment that responds the the ultraviolet component of daylight, the beads have many different uses ranging from scientific testing of (UV) sun block materials to the creation of 'smart' jewellery. Available as a tub containing 10 of each of the 5 colour variations or in separate bags of the individual colours.

Now also available in larger packs of 500 or 2500.