It is probably not the first thing that comes to mind when looking at this collection of particles in black-white-grey tones, but what we see here is actually all about colour. This scanning electron microscopy image depicts supraparticles with a diameter of ~5.4 micrometers, consisting of much smaller silica nanoparticles of 194 nanometers each. At the University of Groningen, PhD student Marina Karsakova is creating these particles and the larger structures they form in a very precise and controlled manner to develop so-called structural pigments. These materials provide colour through the way they reflect the incoming light and are a non-fading, eco-friendly alternative to conventional dyes. The image here reveals that not all supraparticles are identical, some have the desired icosahedral structure, others still show imperfections. For Karsakova, the challenge is to create as many quasi-crystalline icosahedral structures as possible, as these produce very clear, angle-independent colours.