Diez was a versatile artist and worked with bright and focused on decorative effect colors. He also designed Arts and Crafts, medals and plaques, as well as bookplates.
He won in 1905 the 2nd prize in the sweepstakes to sign draft Community Advertising by Ludwig Stollwerck and Otto Henkell. Other winners were the artist Eugen Kirchner, Friedrich Stahl, Albert Klingner, Ludwig Hohl wine, Fritz Klee, Bernhard half riders, Elly Hirsch, Anton Kerschbaumer, Johann Baptist Maier, Georg v. Kürthy, Fritz Helmuth Ehmcke, Paul Leuteritz, Otto Kleinschmidt, Ulrich Hübner, Anton Hoffmann, Otto Ludwig Naegele, Peter Würth, Ernst Oppler, A. Altschul, Jos Ant. Pepin and August Geigenberger.
Diez studied at the School of Applied Arts in Munich and at the Art Academy in Munich under Gabriel von Hackl and Rudolf Seitz. At both institutions he later taught as a professor - in 1907 at the School of Art, from 1925 at the Academy of Fine Arts, the second of which he was president.
From a young age he was an employee and one of the main illustrators of the "Youth - Munich illustrated weekly journal for art and life ", but also worked for the " Simplicissimus ". He was also president of the " Munich Secession ". At times he worked with Richard Dehmel.
For the publisher Schafstein & Co. (later creators stone) Diez illustrated the picture book " Miaulina " (1902 ) and made pictures to " Bogeyman ", " old dog in Santa Claus " and " The faithful Eckart ".
The artist also designed the memorial of the 60th anniversary of the Crown Prince Rupprecht of Bavaria, 1929.
- Eduard Ege
- Franz Paul Glass
- Eugen Maria Cordier