Can anyone help identify this Caliber

Can anyone help me identify this IWC caliber? It is from a Tiffany watch with a Cressarrow case.  Thanks!

Looks like Cal 83 to me 

from what i can tell looks like a cal 83

OK, I did do some research on this before posting. I guess the Cal 83 evolved a little over time. The bridge layout does look like the Cal 83. I just saw the differences in the screw placement and chaton finishing and thought there could be a different caliber. Of course, IWC could have changed the screw placement and finishing for different customers as well.

Hi Tgarnold,
it is a Calibre 86. made in 1923. Only 4800 pcs of this caliber where produced from 1922 to 1938. It has a diameter of 10 lignes.
The Calibre 83 is a 12 ligne calibre in contrast.

br
Cromagnonman

Thanks for the info. I was able to find a spec sheet for the cal 86 and indeed you are correct. The watch is in transit so I couldn't verify its size.

Thank You for the education on Cal 86  :o)