Aug 10, 2018

Rolex Date Just 41, Diameter ??

Hi All,
Im new to the forum so may have posted the same question the wrong location earlier. so forgive me if you see it for the second time.
I have just this week bought a new Rolex Date Just 41mm. When i measure the diameter of the watch with my ruler, it measures 39mm. clearly this is not a great way of measuring the diameter of a watch but i cant see how it can be out be 2mm. Can someone help or advise please?

The best way to measure is to use calipers. And measure from 10 to 4.