instead of BT's tips, I definately use black cardboard (and wear a black sweater, see the pinkish reflection is Chiefs awesome pics) to avoid reflections, and whites to lighten up
I tried expanded polystyrene boards but the rough surface was clearliy visible on the watch...
Basicly it's all about positioning the watch/light(s)
I made a kind of holder to give the watch slight turns from the cameraposition so I can control my reflections
Shooting in RAW gives you the opportunity to "develop" the images multiple times to get the correct tone/darkness on the dial, make a sandwich of the 2 images and dodge/burn