Jaeger-LeCoultre

A few hours ago a friend of mine forced me to revisit the issue of moonphase accuracy on our watches. I understand with some but not 100% clarity that it is governed by the number of teeth on the moonphase wheel of the movement, and that the kind with 59 ... 

I mean, with a 2 to 3 years accuracy. If I remember well, the Master 8 Days Perpetual is 122 years accurate. Best, Nicolas

and are the 122-year variant. The Duometers are, like the Master Calendar and the Duometers, 59 teeth. -Dean

It is the long 122 years type if it is perpetual calendar. That's awesome. Ruckdee

There is some information about the moon phase module on this web site. JLC has been using the IWC Calendar plate for their perpetuals. Quote: That new movement was not to have any ordinary moon phase indication. Traditionally, most watch companies used ...  

I didn't check the web sites again until this minute. Thank you very much for pulling those information for me. I have seen the second link once but failed to find it again. The first one is new to me. Both are very interesting and relevant. Big thanks to... 

You're welcome. A good read. There are some watches whose moon phase is accurate for over 500 years (i.e. Patek 5140G)! And then there is the Ochs und Junior Moon Phase Platina watch with 5 parts, so that it would go off balance by 1 day, a single time in...