After establishing that all the parameters are in a good state and the balance spring is well balanced, we proceed to reassembling the watch and starting the movement. One important thing that the watchmaker must do in assembling the dial is to set the time before the calendar clicks midnight, making sure the click takes place smoothly and precisely. In assembling the hands, he starts with the hand that has the largest hole in diameter then moves to the hand with the smallest hole in diameter (order: hours, GMT, minutes and seconds). Then he proceed to the case, previously polished by a polishing expert who works on all the watches sent by the Hausmann service (the polishing department is in a room separated from of the laboratory). In order to lubricate the joints of the case the technician uses special silicone grease. A very delicate operation is inserting the sapphire crystal, performed with a special tool similar to a press.
By using size appropriate dowels, designed to centre the glass on the calibre and put it flat on the case, manually (via a lever) the watchmaker applies the needed pressure to fix the crystal in its joint. He can now pass to inserting the movement into the case, by removing all traces of dust from the crystal with a vacuum cleaner.
As a rule, the winding crown, when a watch is subjected to full review, is always replaced.