I'm sure the coin is gold and it should be fine. Sometimes UK coins and their affiliates don't have good access to information about their coins at least that's what I found out when looking for information on mine. Don't be discouraged just because you can't find information on it, you just gotta look harder. I think it may be in the link below. good luck!! http://books.google.com/books?id=Tl...the pig coin 1995 1/10th cook islands&f=false
I missed that part where you mentioned the acid test, i don't know strange. What are its dimensions' you can always calculate its relative density and see if it matches gold. Cause it is relatively unknown issue' and not many are going to buy them for collection and would send alarm bells if large quantity shows up for sale. it is going to be bought for melt in which case it would be tested. Gold is dense substance and simple density test would determine whether it is fake. Counterfeiter go after issues' with large population and collector base...