Clusters of uniform‐sized oriented cubic nucleations (OCNs) about 1–2 &mgr;m and local epitaxy crystals (LECs) of 120×150 &mgr;m2on silicon {100} have been obtained by pretreating the substrateinsitufollowed by a typical diamond growth process with a microwave plasma‐assisted chemical vapor deposition approach. The observations made under the scanning electron microscope reveal that the OCNs are not only oriented to one another, but also to the highly faceted LECs at an angle 45° off of the silicon substrate cleavage plane. The x‐ray diffraction data show {400} dominant diamond.