Before you buy gold in today's market, make sure to examine the possible downsides of investing in this asset. JianGuifang/Jerry Jian/Getty Images The investors who bought gold when it was sitting at $2,600 an ounce just 12 months ago made moves that have paid off substantially. Since that point, the price of the precious metal has blown past $5,000, set several new all-time highs and handed investors more than 100% returns in a single year. That's the kind of performance that tends to attract a lot of new money, fast. When an asset moves like that, the conversation generally shifts from whether you should buy in to how much you should buy. Before you start putting money into gold, though, it's worth slowing down. Gold's extraordinary price run over the past year has been powered by real, durable forces: central bank demand, geopolitical instability, dollar uncertainty and an investing public increasingly skeptical of traditional safe havens.…