He worked in various media, favoring new materials and bold geometric forms. Born in Guatemala City on December 5, 1939, painter, sculptor, printmaker, and architect Diaz is a self-taught artist and one of the most important abstract painters in the country.

As an architect and muralist, he accomplished renowned works such as Instituto de Fomento Municipal, Guatemala (1973-1974). He has exhibited widely as a printmaker, painter, and sculptor in Latin America. Diaz co-founded Galería DS (1964), one of the first commercial galleries in Guatemala to promote modern art. Examples of his work can be found in the National Museum of Modern Art in Guatemala.

Among the distinctions which stand out, he received the Latin American Grand Prize at the XI Biennial of Sao Paulo (Brazil) in 1971.