Vintage IWC Cal. 89 authenticity

Hello everyone,

I plan to make a gift to my father for his birthday and I like this (see attachment)  vintage IWC "dress watch" a lot - is completly restored and looks just perfect to me.... but, why there is no "INTERNATIONAL WATCH Co / SWISS stamp inside, on the case back??? Is it normal? Is the movement original? Unfortunatley, I have only this one picture of inside, but can you tell me your opinion about the condition of movement?   If the watch is completly restored, but with original parts (only glass is new), how much is it worth? 

Thank you for your help in advance

Hello Genion,
I have an 89 of about the same vintage, and this looks completely authentc.  I can read the case serial No. as 1374169, so I will date your watch using an app called "Date Your IWC."

Genion,
BTW, there is a mark inside the case back (besides the markings on the movement) that show this to be an IWC--directly in the center of the caseback, you see the "Probus Scafusia" mark.  This means, from what I understand, "Good Work from Schaffhausen."

It would be impossible to comment on the condition of the movement, other than that it looks complete, without a professional examining the watch.   My advice would be to evaluate the seller's information regarding what has been done with the watch, and research the seller's reputation.  Understand that this watch may need a $250-$500 service if it hasn't been serviced recently.

Regards,
Jim

Dear Jim,

thank you very much for your help and  information. The watch is little bit over my budget and the seller is located in another country, but I hope, I can get it. What do you think about the Cal. 89 ? How accurate and robust is it? I have found many positive reviews in internet,...
Anyway,  thank you one more tiem and I will show the pictures of the watch, if I can buy it :) 

Regards 
Genion 

IWC Cal. 89 is a fine, robust and reliable movement.
It was manufactured for a very long time 1946 - 1976 and can be found in fine dress watches as well as the fantastic Pilot Watch Mark XI. 

Thank you very much for the answers! 

today I made prepayment for the watch... my friend will pick up und bring it to me in May... as soon, as I receive the watch, will post the pictures here :)

Regards
Genion