While substantial works were carried out on the analytical characterization of the glasses of the Late Bronze Age and the Roman period, Ptolemaic glass is still far from understood. The present research aims at contributing to fill this gap thanks to a multidisciplinary approach focused on the workshop of Tebtynis (Fayum oasis, Egypt), which was excavated by Carlo Anti in the early 1930s. This project offers a critical interpretation of Anti’s archival documents, in association with the functional and archaeometric investigation of the artifacts which were found in the workshop and that are now preserved at the Egyptian Museum of Turin (Italy). The objects comprise both tools (such as molds, trays, weights) and finished, semi-finished and waste fragments of glass, mainly related to the production of monochrome and polychrome inlays used for the decoration of the liturgical furniture. After a preliminary study of the whole collection (more than 800 fragments > 2mm), a representative selection of 70 objects comprising 144 different types of glass was sampled for in-depth archaeometric investigations. The research required the combined use of a wide range of analytical techniques and methods for data processing: stereoscopic and optical microscopy (SM and OM), confocal laser scanning microscopy (CLSM), scanning electron microscopy equipped with energy dispersive system (SEM-EDS), electron probe micro analysis (EPMA), micro-Raman spectroscopy (µ-Raman), multi-focal imaging (MFI), object-based image analysis (OBIA) and principal component analysis (PCA). The results help to shed new light on Ptolemaic glass-working, constituting the biggest, coherent dataset of this phase analyzed to date. In particular, it was possible to reconstruct the technologies employed for the production of the different classes of glass inlays, investigating the chaîne opératoire and the production markers, also from a micro-textural point of view. A specific interest was also devoted to the identification of the coloring processes and to the characterization of the raw materials, in terms of provenance of the sand source and type of the fluxing agent. The type and quantity of the unreacted relics of the batch, and especially the heavy mineral fraction, suggest an Egyptian production of the base glass, which is well suited for a traditional craft such as that of glass inlays. Moreover, the analytical data show that the Tebtynis collection is mainly constituted by Low Magnesium Glasses (LMG), in accordance with the classic recipes of the Graeco-Roman glass. A small amount of High Magnesium Glasses (HMG) was also found, especially (but not exclusively) connected with the dull red samples, together with intermediate compositions which were interpreted as natron-based glasses modified during the coloring processes. Soda-lime-lead and leaded glasses are present in all color classes, but the highest PbO levels are always associated to sealing-wax red, yellowish-orange and yellow samples. Ionic coloring agents are Cu2+ for light blue and turquoise glasses, Co2+ (sometimes associated to Cu2+) for dark blue glasses, Fe2+ mixed with Fe3+ for transparent green and aqua glasses. The dataset comprises both Mn-decolored and Sb-decolored glasses. The main opacifiers identified in the white, blue, green and yellow glasses are Ca- Na- and Pb-antimoniates, sometimes in solid solution. Both in situ and ex situ technologies were identified, with frequent (but not systematic) associations to specific color-classes. Opaque red glasses were either obtained with nano-sized metallic copper drops (Cu0) or synthetic cuprite (Cu2O). Nano-crystals of cuprous oxide are also responsible for the opaque brown and yellowish-orange colors. A comparison with the analyses performed on the earlier, coeval and later glasses published in the literature showed that the basic recipes and the technological choices for glass-coloring employed during the Ptolemaic period share important links with the Roman production, but also highlighted the great deal of experimentation which is typical of transitional phases.