CARTELLINO — (Italian for small piece of paper) a 5 x 7 cm piece of mosaic paper affixed to the back of a mosaic sheet, visible from the front. It displays section numbers, enabling verification of tesserae placement once pasted.

Cartellinos serve as essential guides for mosaic artists, ensuring accurate alignment and facilitating the assembly of intricate designs. The presence of cartellinos streamlines the construction process, allowing for precise execution and ensuring the overall cohesiveness of the mosaic artwork.