Two concentric rings of colourful glass spheres present the full spectrum of visible light. The outermost ring comprises twenty-four spheres, while the inner ring is composed of thirty-six smaller spheres.  Each sphere presents a step, relative to its neighbours, in a progression through the rainbow: from red at the top, green at the bottom, and yellow and purple to the east and west, the vivid colours seem to emanate from within the glass. 
Eliasson sees these works as optical devices that encourage embodied engagement in the viewer. As the viewer moves around in the space to examine the artwork, the spheres are constantly changing appearance. To create the effect, the back third of each sphere is coated with paint. The painted layer swells to fill the interior of the sphere with bright colour when it is viewed from the front. Seen obliquely, the clarity of the glass re-emerges.