Most of it looks really ugly and I’m wondering if it’s ok to clean them? I know with numismatic coins cleaning is a bad idea but what about bullion? All of the rounds are 1oz silver national bullion coins: - Canadian Maple Leafs - American Eagles - Mexican Libertads - British Britannias - Chinese Pandas - Australian Kookaburras - Somali Elephants - Austrian Philharmonics Stuff like that. If anyone could advise me on this I would very much appreciate it. Thanks! P.S. If it is okay to clean them what should I use?