NEW YORK ( TheStreet) -- Don Dion posts his current insights on the stock, bond, commodity and currency markets in his RealMoney blog, anticipating which ETFs will be in play next. Here are three of his blogs from the past week. What Ever Happened to Gold?Published 7/14/2010 10:37 a.m. EDT Just a few weeks ago, I was talking about the gargantuan SPDR Gold Shares ETF ( GLD) on nearly a daily basis. Trying to address the many questions I received about gold -- from both readers and money-management clients -- I wrote frequent posts with such titles as " Is Gold Buying Overdone?" and " A Short Term Play on Gold," in addition to a two-part series on " Is Your Gold ETF Safe?" As fears surrounding sovereign debt in Europe and a double-dip recession in the U.S. put pressure on equity markets, investors rushed into physically-backed gold ETFs such as GLD and iShares Comex Gold ( IAU). GLD gained $4 billion in net assets during May and more than $2 billion during June. While the uncertainty in the market made me think gold would be popular, the interest in gold ETFs was far beyond my expectations. And then suddenly, the flood of questions stopped. Investors began to feel more comfortable about Europe's debt and currency. Ahead of earnings, investors began to feel bullish about equities, and now they're totally focused elsewhere. To be honest, I'm not surprised. That's why mixed in with my blogs about the recent gold rush, you'll find an entirely different set of posts. " Use Gold, Don't Chase It," " The Curious Case of Commodities Rex" " Stop Chasing the Market" and " Stand By Your Gold ETF" all boil down to one important message: Buy gold for the right reason. When it comes to the immensely popular physically-backed funds like GLD and IAU, these funds are best used as part of a well-diversified portfolio. Since they are taxed as collectibles, GLD and IAU aren't the kind of funds you want to use to chase gold prices by quickly entering and exiting trades. Equity-based gold ETFs like the popular Market Vectors Gold Miners ETF ( GDX) lend themselves better to short-term trading. Physical gold ETFs like GLD are a solid investment for a long-term portfolio, whether they are in the news or not. The best time to begin a long-term investment in gold, in fact, is when everyone else is concerned with other parts of the market. Don't wait until the next gold rush to diversify your portfolio with this precious metal..