This name is borne by the phenomenal Canadian guitarist/folk singer Garnet Rogers. I can never see it as a girl's name because of that. I like it -- it's original without being too weird.
There is a book containing this name within the title: Miss Garnet's Angel by Sally Vickers. However in this instance Garnet is the surname of Miss Julia Garnet.
-- Anonymous User 1/13/2013
I live in Eastern Canada and Garnet is fairly popular around here as a man's name - or at least, it was popular fifty to seventy years ago. I quite like it, might revive it someday!