Rolex Datejust 40 mm: what to check on a used piece

Rolex Datejust 40 mm is the reference in this note. Inspect the crown and the case flank as a pair. The crown should sit centered between the guards, and the guards should be the same height. A guard that is shorter has been filed or knocked. The tube around the crown should not show a pale ring of bare metal unless the whole flank is brushed the same way. Run a fingernail along the lug top. Sharp edges that suddenly go round are a polish job. Polishing is common on a used case and it changes the shape, so describe it instead of ignoring it. Open the clasp and read any numbers stamped inside. They will not always match a serial you hoped to see. Write what is there. Look at the end links for a gap at the case and for screws that are chewed. A chewed screw means the bracelet was removed with the wrong tool. That is a useful fact about the life of the piece. It is not a reason to invent a story about the rest of the watch.

How it differs

Rolex Datejust 40 mm is a dress case. The checks are the date window if it has one, the thinness of the lugs, and the strap or bracelet that was fitted later. A leather strap is a wearable part, not the watch. Look at the lug gap and the keeper. People change straps, hands, and crystals on dress watches. The case engraving is still the reference.

What to check on a used piece

What to check on a used Rolex Datejust 40 mm starts with the engraving. Measure the case. Listings often say 40 mm, and the ruler is the check. Then check end-link play, clasp fold, and whether the hands pass each other. There is no price in this note.

Common mods

Common changes are a new strap, a replaced crown, and a crystal. The date disk, when there is one, should match the dial in color and in height. A disk that sits high or low is a note for a watchmaker, and it is still the same reference.

What people change

On the Rolex Datejust 40 mm, people change the bracelet, the case, or the movement.