Hello. THis is my first post. I'm a (very) amateur collector and am concerned about a possibly spurious coin and would welcome any advice. It's a 1887 gold £5, which looks right, feels right, is in reasonable condition with no obvious wear. Only problem:- it weighs 39.7g instead of about 40g. Is there any way this can be right, or have I been sold a pup? Advice and assistance appreciated, Cheers, Ben