The card says 2011 but being new to this I am not sure if that indicates when it was made or if it is the last time it was serviced.

http://www.ebay.com.au/itm/Omega-Se...D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557Purchases made through these links may earn this site a commission from the eBay Partner Network

 

I'm pretty new as well, but from what little I know, I think the 2531 was introduced in the late 1990s. I don't think the wave dial has been used on the Pro Diver 300m in several years, and the model has used the co-axial escapement for roughly a decade now. (The words "co-axial chronometer" would appear on the dial in that case.) I think you're looking at a 1990s model, serviced in 2011.

 

2011 is Omega's area code for USA. Serial number dates it to 2001 approx.

 

Ah! Thanks for the correction. I do have a lot to learn about my new hobby.