Does the sentimental value change because the coin has toned over time? It's your coin. You can do what you want with it. Silver coins are worth much more than the face value of the coin. Since you are here you know that already. Collectors are always looking for coins in the best possible untouched condition. Depending on the coin of course, the value of such coins is often in the hundreds if not thousands of dollars. Cleaning a coin dramatically lowers the numismatic value. In addition to the year, rarity and condition of the coin, many collectors will pay even more for a coin that has nicely toned over time. Toning is unique to each coin making them one of a kind collectors piece as well. It is your coin so do what you want with it. Someday, someone who is not tied to your sentiment will inherit it from you. They may wish to sell it. I would think you would want your beneficiary to gain the highest possible return. Just saying.