Electron diffraction patterns with <111> incidence of f.c.c. plate-like crystals prepared by gas evaporation technique show forbidden spots such as the 1/3.422 spot. The origin of the spots has been explained in terms of planar defects such as (i) fractional unit cells on (111) surfaces, (ii) repeated thin twins and (iii) stacking faults or hexagonal layers. In the present study, the defect structures are examined by CBED and HRTEM techniques. The <111> CBED pattern of the platelet shows three-fold symmetry for the whole pattern. The dark field patterns of ± 1/3. 422 discs show symmetry of. These features prove that the platelet ha-s no center of symmetry for the three dimensional crystal (3m) and irregular arrangements of twins parallel to (111) planes. The electron micrographs taken along the <110> and <211> directions can give “cross-section” images of the platelet. The images show a few repeated twins with a thickness of several nm. The dark field images taken with the forbidden spots with <111> incidence show weak step contrast. The contrast may be due to fractional unit cells. Consequently, the forbidden spots of the platelet are mostly due to the fractional unit cells.