Osmosis

Hi, I inherited a 35g fine gold Vatican coin as per the title which has sat in a safe since my father in law bought it many decades ago. As I am considering gold as an investment vehicle for 10 years or so could you advise me on your thoughts ? Has this coin maximised it's earning potential ? Would I be better off trading it for a number of UK bullion coins which would all increase in value and be free from CGT in the future ? Or would this coin/medal increase more ? (although I do appreciate that is a bit of an open area) The coin is in mint condition in it's original presentation box from new but there is no grading on it as it is not in a blister pack etc. and has simply been kept as it was purchased. I have seen only one other for sale and noted it's sale price but I would be interested on what value any members here might give it. I am new here so please forgive my question if it is a stupid one but I am investigating investment in gold and coins and learning as I go. Photos attached. Many thanks