As far as I know, only standard life jackets need to be either yellow, orange or red. The terms are confusing. A standard life jacket is the kind that you'll generally find on commercial vessels and those found on cruise boats and ferries (usually hanging from the ceilings). Most people don't own those types. The general boating/fishing public use PFDs or float jackets. These can be of any colour as long as they are approved by the governing authority.