In The Art of Forgiveness, Lovingkindness, and Peace, Jack Kornfield describes an African forgiveness ritual: "In the Babemba tribe of South Africa, when a person acts irresponsibly or unjustly, he is placed in the center of the village, alone and unfettered. All work ceases, and every man, woman, and child in the village gathers in a large circle around the accused individual. Then each person in the tribe speaks to the accused, one at a time, each recalling the good things the person in the center of the circle has done in his lifetime. Every incident, every experience that can be recalled with any detail and accuracy, is recounted. All his positive attributes, good deeds, strengths, and kindnesses are recited carefully and at length. This tribal ceremony often lasts for several days. At the end, the tribal circle is broken, a joyous celebration takes place, and the person is symbolically and literally welcomed back into the tribe."
Even if you cannot stage this extensive a ritual, you can reinforce and encourage forgiveness by reminding the person who has committed a wrong of their positive qualities and contributions.
This practice was developed for the Fetzer Institute by Frederic and Mary Ann Brussat, directors of Spirituality & Practice.