In the vaults underneath the Bank of England there are hundreds upon hundreds of investor-owned gold bars with a combined worth of hundreds of billions of pounds. If you were to examine any one of these at random to try and pinpoint where the gold that comprises it was originally mined, what would you find? Almost certainly nothing. Once gold has been through the refining process, it is practically impossible to independently glean any information about its origins using chemical tests. Apart from in rare cases where databases make differentiation possible via comparisons of isotopic ratios, your investigations into the origin of the gold in your randomly selected bar would prove fruitless - regardless of the depth of your chemical or geological genius.