Diebold was born on 12 December 1961 in Kapfenberg, Austria. She spent much of her high school years reading, skiing, and agonizing over what to major in at the university. She ultimately settled on engineering physics, an area with good job prospects that was also general enough to accommodate a variety of future directions. After completing her diploma in engineering physics (TU Vienna, 1986), she became increasingly enthusiastic about experimental physics while working on her master's thesis, and ultimately completed a Doctor of Technology (Dr. techn.) in this area with Prof. Peter Varga (TU Vienna, 1990).