The exceptional coloring power of nanoparticles (NPs) of gold, silver, or copper due to plasmonic absorption was recognized very early by glassmakers and potters, as were the possibilities of modifying the colors depending on the conditions of preparation. The oldest preserved objects date from the Roman Empire (cups, mosaic tesserae). The Abbasid potters explored how an alternation of layers rich or free of metallic nanoparticles modified the diffraction of light and, therefore, the color of an object depending on the observation conditions: this is the monochrome or polychrome luster, giving objects the appearance of gold. The red and yellow stained-glass windows of the Middle-Ages used copper and silver NPs, respectively. In contrast, those of the 20th century took advantage of the CdS-CdSe solid solution to combine clarity and coloring power. Like China, the monochrome and pink decorations of 18th-century porcelain in Europe use Au° NPs. After having characterized the different NPs by destructive methods (OM, SEM, or TEM), we will show how it is now possible to study colored matter non-invasively, including on site with mobile instruments (Raman and XRF spectrometers). In fact, the rarity and value of certain objects prohibit sampling and make transport to a laboratory very expensive. We will show how the identification of the preparation procedure for Au° NPs can be identified on site by Raman scattering and portable X-ray Fluorescence to document the transfer of know-how concerning the polychrome enameling of porcelain carried out by the French Jesuits at the Manchu Court (Qing Dynasty) at the request of the Kangxi Emperor. The Canton workshops then manufactured export porcelain with a European design and raw materials and recipes imported from Europe. China was already the world's workshop in the 18th century! Colomban, P. The use of metal nanoparticles to produce yellow, red and iridescent colour, from Bronze Age to Present Times in Lustre pottery and glass: Solid state chemistry, spectroscopy and nanostructure, J. Nano Research 2009, 8, 109-132. http://dx.doi.org/10.4028/www.scientific.net/JNanoR.8.109 Sciau, P.; Noé, L.; Colomban P. Metal nanoparticles in contemporary potters’ master pieces: Lustre and red “pigeon blood” potteries as models to understand the ancient pottery, Ceram. Int. 2016, 42(14), 15349-15357. https://doi.org/10.1016/j.ceramint.2016.06.179 Colomban, P.; Simsek Franci, G.; Gironda, M.; d’Abrigeon, P.; Schuhmacher, A.-C. pXRF Data Evaluation Methodology for On-Site Analysis of Precious Artifacts: Cobalt Used in the Blue Decoration of Qing Dynasty Overglazed Porcelain Enameled at Customs District (Guangzhou), Jingdezhen and Zaobanchu (Beijing) Workshops. Heritage 2022, 5, 1752-1778. https://doi.org/10.3390/heritage5030091 Colomban, P.; Simsek Franci, G.; Burlot, J.; Gallet, X.; Zhao, B.; Clais, J.B. Non-Invasive on-Site pXRF Analysis of Coloring Agents, Marks and Enamels of Qing Imperial and Non-Imperial Porcelain. Ceramics 2023, 6, 447-474. https://doi.org/10.3390/ceramics6010026