If you're investing in mercury dimes, remember that the coin's condition is of utmost importance. Any coin which is damaged, marked, scratched, or scuffed will usually suffer a serious reduction in value compared to a coin in finer form. Of course older coins are generally more valuable to collectors, but more than just age can affect the value of a specific coin. The value of a coin depends on many factors besides just how old and how rare it may be. Market value is as much a determination of demand as any other factor.