I bought this on Ebay thinking that they would authenticate it for me. They did not.
eBay authentication program is for complete watches not watch parts; though, I would not have trusted them to be the source of expertise with this anyways.
However, for the $10K purchase price of this case, I highly recommend asking for help before purchasing vs after. How much research/how many 6538’s have you looked at prior to purchasing this?
Based on my limited knowledge, I believe this is a fake. The case looks like it was made yesterday. The lugs look short and thick as opposed to the long slim elegance of a 6538 case. I’m sure someone with more experience will correct me if I’m wrong, but this does not look right.
Edited to add- this 6538 from Wind Vintage for comparison of case shape and bezel font.