Hi, my first post and thanks for letting me join.

Hi, my mother was gifted a Cartier Tank in approximately 1975, it was already been pre owned. It is still running, and is a manual wind. I have no idea on it's age or history, or indeed whether it is of any value. A serial number is engraved, not stamped, and is clearly visible.It has been rattling round in her jewelry box for decades. Any idea on it's age?

Serial is 254762