Forged Tiffany marks on clock faces

Beware of a technique that has been used to apply fraudulent markings to clock faces. The forger uses black "rub-on" lettering. Such lettering comes in sheets sold at art supply stores. Individual letters are transferred to an object off the carrier sheet by pressing or rubbing.

The new marks have been found on genuinely old but unmarked faces to increase the value. So far only forged Tiffany marks have been confirmed but there are probably forgeries of other makers too. New marks can be detected simply by rubbing them lightly with your thumb or fingers. The new lettering disintegrates into small pieces.