Catalytic etching of synthetic diamond crystallites by iron

► Synthetic diamond crystallites were etched by Fe under H2 (0.2 MPa) at 1173 K. ► The etching behavior of the {1 1 1} was different from {1 0 0} planes of the diamond. ► The etching behavior was also affected by the loading amount of iron. ► Iron carbide-like species may also be formed by the etching of diamond by Fe. ► Raman spectroscopy suggests the diamond structure was retained after the etching.