Every watch and every company is different, but this section is designed to help you understand what is and what isn't covered by most warranties and why.

What is typically covered during the warranty period:

Time keeping

Whether quartz or mechanical, it should keep time within its parameters. Quartz watches usually vary less than 30 seconds a month. Mechanical watches should vary less than a couple minutes a month depending on their quality (Certified chronometers are expected to keep within just a few seconds a day)

Batteries

The first battery should last a minimum of one year. If it doesn't usually it is because the watch sat in the showcase a little longer not because there's anything wrong with the watch. (On average, taking into consideration the age of the watch, quality of the watch, and brands of batteries used, a replacement battery will typically last about two years)

Automatic winding

If your mechanical watch is not rewinding on it's own and you are sufficiantly active during the day it should be covered under warranty.If it stops over night or is not keeping proper time this could be the problem (Remember, if you do not wear your watch every day or take it off for a day it needs to be manually wound to ensure full power of the mainspring. What can be accomplished in 10 seconds by winding the crown would take all day for the automatic winding mechanism on your wrist)

Recharging mechanism for quartz watches

kinetic or light .

Water resistance

It can be difficult to determine who is at fault in this area. If the watch does not appear to be mishandled or abused and a water test shows a leak it should be covered under warranty. However most companies will not cover the failure due to chipped or cracked crystals, bent crowns, or damaged gaskets due to improper opening and closing procedures done by incompetent repair persons. Also water resistant watches come with a rating, 30m for basic water resistance ie. splashes and washing hands, 50m for surface swimming, 100m for snorkaling or shallow scuba diving, and 200m and 300m for deep water scuba diving. If the service center tests the watch to its rated depth and it passes it will be assumed that the crown was not properly closed and might not be covered

What is typically not covered:

Crystals

Crystals, no matter what they are made of can be damaged at any time. A brand new crystal cannot be expected to be any stronger than one that is 5 years old and chipping, scratching or shattering against a brick wall or concrete floor can happen the first day.

Crowns

Crowns can be bent, broken, or crushed at any time. I know of at least 2 instances where  domestic birds bit the crown off the watch while sitting on their owners' arm! If it is a screw down type and will not tighten down within a short period the company will often replace it once provided nothing else is wrong with the watch-check with the manufacturer.

Bands

Straps or metal bands might be covered if it appears it fell apart due to manufacturer's defect. If it gets torn off your arm in an accident-probably not.