Panerai stunned the world of watchmaking when they introduced a wristwatch with a bronze case. It was chosen with an emphasis on deep sea diving and the old bronze machinery that used to be used in diving. Panerai used this material because bronze develops a rich green patina over the years and is highly water-resistant. The present watch has developed a rich green patina that matches beautifully with the special edition dark green dial which was developed specifically for the Bronzo.