The paperwork is always the first option for locating a watch model number, but unfortunately many times the papers are misplaced or lost. While some watches will not have a watch model number on the physical watch case, surprisingly, many of them do. So… how do you find a watch model number? The answer? It depends on the brand. For example, it is a common mistake on Cartier watches to blur out the case number instead of the watch serial number on online eBay listings. However, without knowing it, many people mistake the watch serial number as the watch model number. Luxury watches come with a variety of numbers associated with them on the paperwork, case back, chronometer certificate etc., but which numbers are really significant? We are often afraid of giving the serial number away because of the growing replica market that has been taking these numbers and using them in a disingenuous way.