There are two elements to consider when determining the value of an antique Omega pocket watch: condition and demand. Omega is one of the best Swiss watch brands ever made and is highly desirable. An Omega in excellent condition can command top dollar. However, top dollar in the pocket watch collecting world generally doesn't exceed £650 as of 2010. Value only matters when the buyer and seller agree on a price, and much of that stems from the buyer's emotional attachment to the watch. Collecting pocket watches is a poor investment because most brands are common.
Research the market for antique Omega pocket watches. There are hundreds for sale on Internet websites. View the year manufactured, condition, materials used to make the watch and the price to determine the Omega's overall value.
Buy the latest edition of a watch price guide. Guides list Omega models by year and have a stated value. These valuations, however, are generally out of date by the time the guide is published.
Visit Internet auction sites. Follow bidding on Omega pocket watches and pay attention to the final prices. Beware that auction prices are generally lower than pocket watches sold at brick and mortar shops because they usually have no warranty.
Visit brick and mortar shops that specialise in vintage watches. Prices are generally high because many shops have a watchmaker who services the watch and may offer a warranty. Omega pocket watches generally sell for between £195 and £390.
Examine with a jeweller's loupe or magnifying glass the crystal, which is the glass covering the dial, for cracks or scratches. Examine the dial for ageing, patina or spotting. Light patina won't hurt value. Heavy spotting devalues the watch.
Inspect the hands to determine if they are in good condition and are original. You can determine originality by examining the model in the price guide or similar models at a seller's website. Non-original hands or dial severely devalues the watch.
Inspect with a jeweller's loupe the case for nicks, scratches and dents. Expect the case to have some wear and tear. However, large dents render the watch almost worthless.
Use a case blade to open the case back of the Omega. Inside should be a jeweller's hallmark if the case is silver. Compare the hallmark to hallmarks in a jeweller's hallmark guide to determine the watch's rarity and quality. Search gold cases for 9K, 10K, 14K, or 18k for gold content quality.
Note that cases made of gunmetal, solid silver, 9K or 10K gold fill do little to enhance the value. A 14k gold filled case may bump up the value. A case made of 18k gold significantly increases the value of the watch only because the watch is worth at least its weight in gold.
Inspect the inside of the case cover or back of the watch case for personal engravings. Personal inscriptions of strangers only devalue the watch.
It's unlikely you can sell a pocket watch for the price you bought it.
Beware of Omega watches cobbled together from different sources. These are fakes and have no value.