I've been looking for any information on this Matte style case. Can't seem to find another example with a similar type of Case Coating/Polish. Could it be a Prototype or a rare variant? Any help would be greatly appreciated. Exact Reference is 145.016-68.
I asked Gemini about the reference # and the term Inoxytable
While "Acer Inoxydable" itself might not be a specific model name in official Omega history, it's highly likely you're encountering this term in the context of vintage Omega watches.
Translation: "Acer Inoxydable" is French for "Stainless Steel."
TLDR - someone sand blasted it at some point, it did not leave the factory that way as there are signs of polishing on the case which would cause the case to not be matte. So the case was worked on before it was turned matte.