Many investors looking to diversify their investments away from stocks and bonds have done so by adding exposure to commodities to their portfolios. Silver is a particularly interesting commodity, in that it straddles the fence between the precious metals and base metals. Like gold, it's commonly used in jewelry, yet silver's relatively low price allows it to be commonly used in a variety of industrial applications as well.There are several ways to invest in silver, such as by buying physical bullion or futures contracts.