A large number of diamond crystals with tetrapod-like form were obtained when a tungsten thin plate was used as the substrate of hot-filament-assisted chemical vapor deposition. In this case, the substrate was covered by hexagonal tungsten carbide (WC) thin films and subsequently diamond crystals grew on them by facing its own {111} to the substrate. The sites of carbon atoms on {111} of diamond are in good accord with those on (001) of WC. Hence WC microcrystals provided nucleation sites for subsequent diamond growth. Namely on (001) of WC, {111} of diamond grew epitaxially, constructing the coincidence site lattice (CSL).