To make a comparison that may be down on some owners of expensive watches, a clock with quartz cheap - 5-6 hundred thousand lei - can, or rather is more accurate than a watch very complicated and expensive to order of thousands or tens of thousands of euros, but the driver, such as Rolex, Omega, Maurice Lacroix, etc..
In mechanical watches, there are two types of precision, to say this: watches Chronometer Certificate or have not Chronometer.
This certificate "Official Swiss Chronometer" is granted by a Swiss institute is responsible for certifying mechanisms and called Controle Officiel Suisse des Chronometres, abbreviated COSC. No clock is not entitled to wear the logo of "Chronometer" so long as this does not license. Tests are subject to these watches to wear the logo are quite a lot, at number seven, which I have to insir here What is important to know, is the standard for precision watches COSC certified, it is -4 / 6 sec/24 h.
On the other watches modern maximum allowed by producers in general are -15 20 sec/24h.
So the reasonable limits to which you can expect from quality watches, after a proper repair are:
Error rate / type clock Acceptable Good Very good
Watch old - / 60 sec/24h - / + 20 sec/24h - / 5 sec/24
Modern watches have not -15 / +20 sec/24h - / + 10 sec/24h - / 3 sec/24h
Modern watches certified -4 / 6 sec/24h - / 3 sec/24h - / + 1 sec/24h
From these data are exceptional watches Russian, for which the producer and give up errors -45 / +120 sec/24h /.
Data in the table for information.
If the watch is included in the column of "Acceptable" means that the clock is within the limits accepted by the producers and the clock can not be considered defective.
After repair a clock is good to ask a ceasornicarului printing error rate in at least 2 positions of the clock with the dial up and down with the crown, most devices adjustment providing this opportunity.