Hi I'm french. I've got this watch from my grandfather. I think this watch was bought in the 1920'. Please can you date it ? It runs perfectly. The box is in steel. The diameter is 50 mm and the thickness is 13 mm. The number of the box is : 6258824.D The number of the gear is 5494412 There are two very little marks inside with a swan Thank you for your reply.
Based on this rudimentary chart http://chronomaddox.com/omega_serial_numbers.html, I would guess that your watch was made around 1920. Although you state that the box/case is steel, the "A" beside the movement/serial number suggests that the watch originally came in a silver (argent) case. Furthermore, a swan can be found on many silver watch cases that were to be imported into France according to David Boettcher. http://www.vintagewatchstraps.com/casemarks.php Lastly, I believe that the dial is correct as the "Suisse" marking also suggests that the watch originally went to France.
On the chart the number 5000000 began in 1916. But my grandfather was soldier since 1914, wounded and prisoner until November 1918 and he began to earn money after 1920. You're right : the case is in silver and I have cleaned it. Now it's wonderful. Thank you very much.