Glass has the ability to refract, reflect, and transmit light following geometrical optics, and is therefore a magical substance. It can be also be ground in certain ways and used for optical instruments, spectacles, magnifying glasses, binoculars, telescopes. It can be heated and blown into decorative and intricate shapes, toughened to make windows, and coloured using various chemicals. The PiP shows the magnifying properties of glass. The thistle is etched into the base of the paperweight and is magnified by the half sphere of glass. The red line has been refracted.