A Curious Prism

I spotted a heavy glass paperweight resting beside a stack of mail, catching the afternoon sun and scattering tiny rainbow patches across the tabletop! Fascinated by the bright colors, I floated close and wiggled my fingers to gather the light into a dancing spark. 'Alakazoom!' I whispered, giving a hopeful flick of my wrists. Well, by the rings of Trolla, the light didn't gather into a ball at all—instead, the glass gave a tiny wobble and cast a vivid beam straight across an open envelope, illuminating a shimmering spectrum right before my eyes!