For your Ingenieur, I take it that you do not know the reference / edition / series number/name ? If so, can u identify it from this very useful website by the pictures?
Your inherited watch presumably Case number 1,626,437 would make it: "The case was most probably produced around 1963 and delivered up to 1964."
Closeup pics of the dial, casing, movement would help, if u could share them here on this forum.
The case number and movement number will also assist greatly. For pocket watches, to see the movement number you would need to open up the back of the pocket watch, which a good watchmaker can do for you without harming the timepiece.
Erstwhile, these below can assist for vintage / older watches:
DateYourIWC by case and movement number (I prefer the applet version at the bottom), created by Marco Schönenberger
Vintage Catalogs
Instructions found here on how you can also order an extract from IWC archives to verify authenticity.
Visit our moderator Michael Friedberg's excellent website on pocket watches, and compare both the dial and the movement designs. Many pocket watches have similar dials, so you may wish to look more for similarities in movement design.
For active collections & editions you can also consult the IWC Workbook Search, an application created by Stefan Weeber. Please read its very useful Help page too.
If you know the IWC watch reference but would like to “date” it, i.e. find out when/which year it was placed in an IWC Catalogue, please consult Greg Steer's fantastic catalogue found here.
Picture Uploading - A Snappy Guide
Step One: most people sign up for a free host at www.photobucket.com
Step Two: Upload your pic, preferably in 640x480 size
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.

Step Four: 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.