How can I take tarnish off a pure silver coin?

Look people say don't wash your coins or don't clean your coins, when you see coins that are .9999 there are only 2 types of coins that are that fine of silver, Rounds, or Bullion coins i don't think there was coins ever that pure since probably the silver age that was long long time ago. But i can say yours could be either bullion or a round and those are safe to clean, if its brownish you can try baking soda its a very fine abrasive and it makes any dirty silver coin look nice and shinny silvery look again. But you know if its like really tarnished like black kinda tarnish theres a trick i learned on youtube. All you need to do is in a glass bowl use really hot water put a aluminum into the hot water with salt and baking soda, put the coin in and it will be tarnish free. Now this is for the black tarnish if its brown kinda thing its usually dirt or oil from your hand and not really silver tarnish but to prevent this i always wear a cotton gloves when handling my silver because oil from hand is slightly acidic and isnt good for coins at all. Now your coin won't devalue because if you collect silver the silver value is always there, just remember this. Silver is always silver doesnt matter how old or how bad of a condition is it will always retain your wealth. But still its better to be proactive so it doesnt have to be washed as much.