Gilding on 18th century mugs

My first post on this forum and am hoping someone might have a definitive answer for me on this topic!

I have recently started to collect Georgian silverware, and am am looking to buy a really fine 18th century mug. I have seen examples with gilded interiors and some without. Did 18th century examples ever have gilded interiors? Some dealers tell me that this was never the case and the gilding must have taken place at a later date, whilst I have been offered gilded examples by dealers who claim that the interiors are original!

Visually, the gilded examples are very attractive but I would really like to buy what is authentic.

I would very much appreciate any help in seeking out the truth in this!