1868 s half dime

Hello, I have a 1868 half dime. I found this going through my grandfathers things the other day....He was a coin collector and this is the oldest one that he had so I'm guessing its the most valuable? As you can tell i know nothing about coins, I do know that it looks great for as old as it is and it comes in a plastic coin case of which i opened to scan the picture. Hopefully it didn't ruin any value by opening it..GUARANTEED AUTHENTIC!!!.....anyway, ....