Although many ancient civilizations are known to have made use of polychromy on sculptures and in general on stone artifacts, today much of these colours went lost. For this reason, in the minds of a very large majority, the original stones have remained un-coloured until today. The small amount of these traces lead to a new approach for their characterization in order to limit sampling and hopefully, avoiding it. The non-invasive approach permits the examination of a very large number of artworks with a virtually limitless number of analytical acquisitions allowing to perform measurements in situ. Already during the measurement process, this approach leads to a fundamental exchange of views among scientists, archaeologist, conservators and art hystorians. The application of protocols based on imaging techniques (i.e. UV Fluorescence, Visible Induced Luminescence-VIL) integrated with data obtained from single spot techniques such as X-Ray fluorescence (XRF), Fibre Optic Reflectance Spectroscopy (FORS) and Total Reflection Infrared Spectroscopy (TR FTIR), provides high-quality information. In this paper some examples of analyses conducted in different contexts from museums to archaeological sites will be presented. These analyses are included in a wider research project aimed to enlighten the use of colours on the sculptures in ancient time and to better define materials used in the past.
Bracci et al. (2019) studied this question.