TSC Ratings provides exclusive stock, ETF and mutual fund ratings and commentary based on award-winning, proprietary tools. Its "safety first" approach to investing aims to reduce risk while seeking solid outperformance on a total return basis.Four of the 10 top-rated exchange traded funds invest in gold and other precious metals. Another three bet against the U.S. dollar by taking stakes in foreign currencies. The list, which excludes fixed-income ETFs, is based on performance data as of May 31. Last month, gold rallied 10% to $979 an ounce while the U.S. Dollar Index retreated 6.2% against major currencies such as the euro, Japanese yen, British pound and Canadian dollar. Inflation fears and weakness in the U.S. dollar stoked demand for gold in May, pushing prices higher. The situation reversed in June with gold prices pulling back as the dollar strengthens. Russian Finance Minister Alexei Kudrin said at Saturday's G8 meeting that he expects the dollar to gain more value. This provides investors with an opportunity to take advantage of potential dips in the SPDR Gold Trust ( GLD) or its smaller rival, the iShares COMEX Gold Trust ( IAU). These gold bullion-hoarding ETFs earned our top rating of A-plus as did the PowerShares DB Gold Fund ( DGL) and PowerShares DB Precious Metals Fund ( DBP).