1818 George III Coin [solved]

Yet another donation to Oxfam in Exeter that I can't identify ( or price). I've done a Numista image search but it didn't produce anything useful. 

Weight is around 4.15 gm. Diameter 24 mm

Any help, as ever, much appreciated:

Check against this one 1 Shilling - George III (New coinage) - United Kingdom – Numista

1818 is a very good year.

My only hesitation is that the coin seems to have a god tinge to it, although I realise none of the gold coins of 1818 are the right size/weight.

Contemporary counterfeit

Oh dear. I want to sell this in our Oxfam shop. If it's a counterfeit it would not be good to sell it,; if it's real then I can and make more valuable funds for oXfam.

Don't know what to do!!

On the Numista page cited above, the weight of a George III shilling is listed as 5.66 g. Your coin is way low in weight (1.5 grams low). Wear could account for maybe 0.3 or 0.4 grams, but the very low weight indicates it's unfortunately a fake.  

Thanks. This makes sense that it is a counterfeit. Next time I can't find an exact match with weight/dimesions I'll consider the counterfeit option :-)

N#359339

Sell it as such.

Thast's very helpful - thanks