Hi, Welcome to the forum and this great Hobby, Sport, whatever you would like to call it. Professionally cleaning a coin, I am no expert. If the coin is valuable or scarce, I would not recommend any attempts to clean it yourself. I have cleaned a few silver coins myself only because I wanted to and they were not of any significant value. I just wanted a brite shiney silver coin. I have used two methods that work well for me. 1. I use some aluminum foil and some white vinager. Take a silver coin that is blackened and place it on a piece of aluminum foil. Place a few drops of distilled vinegar on top of the coin or any piece of silver and cover it up with the aluminum foil. Wait a few minutes and check it. You will see the black disapearing. It may take a few times to remove all of the black. 2. I have used baking soda and a tooth brush to remove the black as well. Keep in mind that these methods I use only on a coin which does not have any significant value. Also remember that If you do have a valuable coin and you want to have it Authenticated and graded by a professional grading service, these cleaning methods would definatley lower the value of the coin. Some grading services will not grade a coin that has been cleaned with the likes of certain chemicals or abrasives. The grading tests that they do, will reveal cleanings such as I have mentioned. Metal polish is an abrasive as well. Yes it will make an old coin look brilliant, but will also damage any fine detail the coin may have. I have heard that most coin dealers will not buy a coin if they know that it has been cleaned. Check many sources, coin dealers, coin experts ect. You have a great looking coin there, be careful not to damage it. Try to learn everything you can about preserving your coins, they may be worth a lot of $$$$. I hope this helps you. Good luck, HH (happy hunting), Art...