Testimonio is also a personal commitment. César Olmos, a reputed engraver with many exhibitions and prizes to his credit (Ljubljana, 1st Prize in Engraving at the 3rd Paris Biennial, 1st Prize at the 7th São Paulo Biennial, and the Dziennik Poliski 1st Prize at Cracow) has turned the facsimile into an extension of the art of engraving. Born in Valladolid in 1936, Olmos studied at the San Fernando School in Madrid and was later given awards by the Ministry of Education and the San Fernando Royal Academy of Fine Arts.

From his base at Testimonio, César Olmos has worked with a number of Spanish, European and Latin American institutions to produce several series of publications. The Tabula Americae Collection recaptures for the bibliophile both pre-Columbian treasures and the adventure of the Discovery of the New World. Thesaurus Americae is a selection of representative works from each Latin American country, ranging from New World chronicles and scientific studies of flora and fauna, to poetry and didactic works. The Scriptorium Collection brings together texts which symbolise a common European culture.