Hi,
Hazarding a guess, would this watch have been purchased around mid-late 90s ?
Pics would help, if u could share them here on this forum.
Erstwhile, these too can assist:
DateYourIWC by case and movement number (I prefer the applet version at the bottom)
Vintage Catalogs
Instructions found here on how you can also order an extract from IWC archives to verify authenticity.
To post pics:
Picture Uploading - A Snappy Guide
Quick Step One: most people sign up for a free host at www.photobucket.com
Quick Step Two: Upload your pic, preferably in 640x480 size
Quick Step Three: Look for this box below and click on the URL beside IMG Code, and paste it directly in ‘Your Comment’ box when writing a new comment in the forum.

Quick Step Four: check, check, check that you have successfully uploaded the pic (like I have done with the image directly above :) by using the preview button i.e. clicking on the ‘tick’, just above the ‘Your Comment’ box. And you’re done !
If you are still facing issues, kindly consult this earlier discussion with clearer and more in depth instructions by two esteemed members.