I'm not fond of it. I find it clumsy. I'd never use it. The only nickname I can think of is
Gerry or
Jerry. I had a friend named
Geraldine when I was middle school age and I can remember her telling me that her mother had had several miscarriages prior to her birth so when she was pregnant with her she prayed to St.
Gerard, had a successful pregnancy, and named her
Geraldine for that reason. I guess because there's no such name as Gerardine? Also I work with a young
Gerard but he goes by a totally unrelated nickname.