Yours is much lighter in colour as you say. I wonder if Hoglund always stuck to the same dark, almost burnt amber colour ? The outside surface of my mug is very smooth as you can see in the photos . The inside surface of the mug is all lumps & bumps though. I guess you have checked the base for any hand written marks, mine are very difficult to see and yours has quite a bit of age-related wear .
Cheers, Mike