Abstract: The invention is related to a watch case equipped with a decoration piece (50) which has the particularity of being difficult to machine and having moreover dimensions of rather wide tolerances, namely plus or minus about a tenth of a millimeter around a reference dimension, whereas the manufacturers of the watch cases are able to ascertain usually a precision in the order of a hundredth of a millimeter. This handicap is overcome in providing a clearance between the decoration piece and the adjacent elements (20, 30), namely the middle of the watch and the bottom, and thanks to means (60, 70) ascertaining the maintenance of these clearances, these means exerting at the same time the functions of tightness and of shock dampening where the shocks occur on the clockwork-movement (10) or on the decoration piece (50), or on both.