The only thing that I see wrong is the big blob in the field...what is it do you know? maybe its something that can come off with a simple long soak in distilled water? There are also other ways to soak a silver coin and remove crud that would do nothing to the coin anybody would be able to notice (as much as they like to think they would ). there are a few on ebay..this one looks stunning: http://cgi.ebay.com/PANAMA-1979-20-...ryZ45147QQssPageNameZWDVWQQrdZ1QQcmdZViewItem http://cgi.ebay.com/Panama-1978-20-...ryZ45147QQrdZ1QQssPageNameZWD1VQQcmdZViewItem
If you know that conversion you're already off to a good start. Especially when it comes to avoiding speeding tickets while travelling in Canada