Michel Pastoureau traces a journey full of blue, from Antiquity to the present days, ranging from lack of interest to the success of the blue colour in Europe. My contribution follows a more limited course in Ravenna, the fifth to sixth century, following a reverse path of the blue colour, from ‘success’ to ‘reverse’ … In the mosaics that decorate the oldest monuments of Ravenna, artists have used a wide range of pieces made of blue-coloured glass with many shades and tones, which are in a (...)