In order to figure out how old a Ball jar is, you need to compare the logo found on the jar to a chart of what years Ball used that logo. Ball jars has changed its logo several times since the company was founded.
For instance, if the logo is a large 'C' with "MCBB" inside of it, then that jar was likely made in 1885 or 1886. If the jar has "Ball" written in a script type with the registered trademark symbol on the right side of the logo, the jar is fairly new and was made sometime between 1975 and the present year. The only difference between jars made from 1960 to 1975 and the jars made after 1975 is the addition of the registered trademark symbol.