Nitrogen ions were implanted into diamond films formed by microwave plasma CVD. A color cathodoluminescence (CL) system were used to investigate the emission centers of as implanted and the subsequent annealed films. A zero-phono-line (ZPL) from the implanted N+ was observed at 3.19 eV. After annealing, a ZPL at 2.16 eV and a strong emission center in the violet region with a ZPL at 3.19 eV and phonon replicas were observed. The color CL images of the annealed films show that an orange-red color emission comes only from the {100} sectors because of the difference in crystal quality between the {100} and {111} sectors.