His artistic approach favoured mythological and allegorical subjects, such as those seen in Vulcanus or Venus and Adonis. Diamantini used strong contrasts between shadow and light to define form and create a sense of physical presence. His compositions often feature muscular figures and dynamic arrangements that suggest movement. The clarity of his line work in etchings like Allegorie van de nacht demonstrates his ability to translate complex narratives into clear visual arrangements.

Modern collectors value Diamantini for the graphic strength of his compositions. His etchings and paintings offer a sense of classical order combined with the energy of the Venetian Baroque. These works provide a sophisticated visual anchor in contemporary homes, where the stark tonal ranges of his prints complement various decor styles. His depictions of Fortune and Hercules remain relevant through their clear, classical symbolism.