Dupont fuel is measured to specific lighters. The fakes that I have all seen have the wording and numbers stamped in one go. I've been trying to research a way to verify the serial number but haven't had any luck. Dupont continues its world tour of the decorative arts with the New York 5th Avenue collection. S.T Dupont New York Fifth Ave 5 Piece Pen and Lighter Set: S.T.