I see what you mean that the case looks like it has plating wear, but pictures can lie.
Surely not every Tiffany watch posted in here is a fake...even a presentation watch???
Of course the faker could have added the presentation engraving to add authenticity..... but
a deep engraving like this on a plated watch and the plating would be noticed as the brass would
tarnish a different colour and the plating would be noticed at the engravings edges.
A quick search of the internet turned up this watch which also has the T-120 gold case.
Could be another 'fake' I suppose....but I've never saw base metal cases which were sand cast
as these gold cases seem to be.