From this month’s Q&A from the Chicago Manual of Style:

Q. I am confused about the capitalization of giclée, which is a type of computer-generated art print. I see it both ways. It isn’t a proper noun or anyone’s name, so I don’t see why anyone would capitalize it. Can you weigh in? It is not in my dictionary.

A. People probably cap giclée for the same reason they cap president, chapter, or impressionism. We don’t know what that reason would be, so we lowercase it.