IWC was an axis from which operated JLC and Lange and iWC.
The inhouse tests allowed a flexibility of monitoring materials that were ordered from sub contractors, this was then passed on to in house manufacture or onwards to other sub contractors for cutting/polishing/manufacture etc etc.
Homologation then proceeded to inspect and test parts, bridges, screws, crystals, straps, and eventually prototyping fuly assembled watches.
Of course, fully functional watches were tested in house as well.
These invloves many stages, of which I will slowly post up one at a time in this forum.
Meanwhile, also look thru the Ulysse Nardin, Genta and Bulgari forums where other homologation processes take place, but along a different path.
The IWC homolation is, IMHO, one of the most orientated towards product function in the field, a most military approach that was a brainchild of several men of the past, Gunther Blumlein, Kurt Klaus, Richard Habring, and many others. It is designed to minimse returns, failures, and to detect stoppages over long periods extending beyond 20 years.
The man who runs the show...a post later.