Nope, one layer, one shot.
I tend not to separate a shot into layers as much as I am very comfortable with selecting areas and relying on multiple undos if there's a deal-breaker.
Here's what I did: Noise Ninja to get rid of the CCD noise (always do this first) and then clone tool to tidy up dust specs and the like, then hit the levels palette for the first of many times and block off the range I want my whitest and blackest to be. Check your clean-up looks good even with changed levels.
Then, take the airbrush to the edge where the stand is visible and remove all traces of imperfection in the background. Whitewash the lot by selecting the watch and not much else with the lasso, invert selection, delete.
Then, make an elliptical selection over the bezel insert, use the selection transformation to select just the bezel insert. This doesn't need to be pixel perfect as the next step is to invert and feather the selection. Once you have everything but the bezel, desaturate using the hue/saturation palette, bringing out the steel grey.
Re-invert the selection and tweak the levels for the bezel insert, ignoring the results for the dial as we'll be doing that next. It's mostly a gamma modification you need here as opposed to white/black levels.
At this point, you make an elliptical selection over the crystal and transform selection (scale/rotate, etc) to select the dial/crystal. Feather slightly (4-8px only) to make any missed edges less important. Use levels once more to get the dial to the right depth of black. Desaturate a little to get rid of any colours, although this would not be wise if you had a red sub or GMT, and there you'd select shadows and inverted colour ranges to desaturate.
Astute readers will realise at this point the only area with any colour is the bezel insert, and this is visible in the pearl. Subtle enough to hint that this isn't a black-and-white image, which strengthens the metallic look of the steel colours.
At this point, I painted over the one part where the stand insert was showing using masks and the clone tool.
Once this is done, I loosely selected everything at the front, ie, the face, the crown and the first few links either way, and feathered the selection, inverted it so the background portions of the watch were selected and used gaussian blur to enhance the out-of-focus depth of field. I also lightened the out-of-focus area to draw attention away from it.
Lastly, I slapped my drop-shadow P in the bottom-right and hit save for web.
Here is the original as it came out of the camera: