To obtain p‐type doping of diamond through B ion implantation, thermal treatments are necessary to reconstruct the diamond lattice and to locate B atoms in substitutional lattice positions. The present contribution evaluates by STEM‐EELS and CL spectroscopy the amorphisation of diamond lattice under the B+ bombardment and its subsequent reconstruction after the thermal treatment. In addition, TEM observations allowed localizing the boron spatial distribution. Carbon‐related peaks of EELS spectroscopy shows a nearly complete recovery of the diamond lattice after thermal treatment. Indeed, at 1600 °C, sp2/sp3 ratio in implanted regions changes from 0.56 to 0.18 (0.15 value was measured before implantation). On the other hand, CL spectroscopy reveals how A‐Band and free exciton emission peaks, which are quenched by B+ implantation, recover after annealing. Boron ion implantation was used to create ohmic contacts in two different diamond samples, treated with different annealing velocities. Crystalline reconstruction, evidenced by TEM data explains the related electric behaviour. Nanoscale evidences of amorphisation, lattice reconstruction and dopant activation are presented and discussed in this work.