Hi,
I assume the reference to the catalogue is this one?
N#403842
The quality of that silver medal is very different to yours, the standard bearers of lion and unicorn are much more expertly engraved, for instance.
Also yours has a globe at the bottom, which doesn't appear in the above, or one with a similar reverse:
N#403831
I'm guessing that yours isn't precious metal - some kind of white metal or pewter?
It seems strange that anyone would fake this as it would have little value?
I'd be more likely to suggest that it has been copied inexpertly, but who knows?
Whatever, it should be in the catalogue, I think.
Cheers
Simon