On 6 December 2025, we shall be hosted by the Museum of Natural History in Rosignano Marittimo, partner of the Va3SCoDi project, to discuss a topic which—rather like politics or religion—never fails to provoke disagreement: colours! Indeed, we have long been led to believe that a colour may be associated with a single, quantifiable and objective value, whereas in truth our perception is profoundly subjective. It depends on physiological factors and on the conditions of our surroundings, on the light source, and on the very object we are observing.
Take this image. Does the blue on the left appear to you the same as the blue on the right?
No—on the right it seems markedly darker. The yellow, too, appears different.
And yet they are, in fact, identical colours. For this reason, instruments capable of quantifying the colour of a surface have been devised, developed originally at the beginning of the XX century from the colorimeters and the spectrophotometer. We shall therefore discuss how such instruments came into being, tracing their development through the evolution of historical scientific apparatus.
These instruments will then be directed toward a rather particular subject: minerals. Why do minerals assume various colours, and why do they change colours depending on illumination? These are further topics we shall address, related to the manifold interactions between light and matter. The intrinsic beauty of these aggregates of matter has led not only to their being regarded as precious, but also to their being employed in the creation of works of art—sometimes in their natural state, and at other times ground and incorporated into painted surfaces in the form of pigments.