Physician-investors are always looking for portfolio diversity, but often don't know which direction to look. A current BusinessWeek article delves into some assets that have been touted as "hot buys" but may in reality prove to be potential traps. The following are some investments to approach with caution:

•Timber looks like an attractive commodity because of stable logging income and the value of growing trees. Investors should beware, however, that tree growth won't speed up so you can cash out, and timber investments require heavy management and capital gains.

•Rare coins, like timber, move in opposition with bonds and have little in common with stocks. But, coins must be kept safely stored from theft or damage at all times, incurring extra costs, like deposit box fees. And, coins require costly expert appraisals and are subject to a capital gains tax rate.

•Gold is a classic commodity for alternative investors and seems like an appealing option, but gold can maintain its value for years without fluctuation. That means you can get stuck holding on to gold without gains for longer than your long-term goals.

•International real estate could be the most lucrative alternative to stocks and bonds. But the travel expenses, foreign connections, and resources it requires often negate its overall value.