The method optimizes the process of making mosaics, in terms of the quality and similarity of the image that is produced, making it possible to work manually, semi-automatically or fully automatically with optimum results. This is achieved by analyzing each of the pieces that make up the tesserae according to a large number of parameters, including the existence of marks and their position in the pieces, and assigning a storage location to each of them. Computer software is used to divide the image to be depicted into graphic units, the characteristics of which are also analyzed, comparing them with the available pieces and assigning the most similar piece thereto according to the available pieces and within a tolerance range. The final appearance of the mosaic is then displayed, it being possible to make changes to the assignation of pieces manually if necessary. Said software then assigns the exact position of each piece in the mosaic to be formed, based on the storage position of said pieces. The pieces are then glued in place by any conventional means.