There are quite a number of reports at WUS HAQ - generally the 5 seconds/year models from Citizen and Seiko are considered to be the top level of self-accuracy still in production. There was a Citizen Crystron Mega which was claimed to be around 3 seconds/year but I have very serious doubts about maintaining that performance. Even today the accuracy performance is subject to 'aging', and even in very high end models a recalibration might be needed after like 5-10 years (which can be easier done in some HAQ Swiss models but very few models from JP, where you need to send the watch back to the manufacturer :roll: ).Originally Posted by Omegamanic