On French silver jewelry, the most often-seen mark is the boar s head, the mark of the Paris Assay Office, indicating a fineness of 800 or higher on small articles (such as jewelry). This mark was in use from 1838 to 1961.n French silver jewelry, the most often-seen mark is the boar s head, the mark of the Paris Assay Office, indicating a fineness of 800 or higher on small articles (such as jewelry). This mark was in use from 1838 to 1961.