I got this coin a while back and was wondering if any of the coin collectors on the ChipBoard can provide any information as to its value. It's a silver coin dates 1885 with a denomination of 20 centavos. It's from the Bolivian Republic and bears the Potosi mint mark. It's about the size of a nickel. Looks to be in excellent condition, but I'm no judge. Any input would be appreciated. Thanks.