In the movie The American, Mathilde, played by dutch actress Thekla Reuten, wears a Casio LTP1165A-1C black casual ladies watch, with metal band and black dial (color code 1C). This simple but stylish Casio watch (with the Casio 1330 module) is water resistant, measures 32 x 21 x 7mm and weights 69 gram. The same model is available with a pink dial (color code 4C) or blue dial (color code 2C). A gold version, or black with chrystals on the 12 and 6 o'clock are also available, see slideshow below for an overview.

Get the watch as seen in the film at Amazon.com for only $20.

George Clooney wears a slightly more expensive watch in the same film, an Omega Speedmaster.

Thanks to sruzgar for the ID