Irresponsible fiscal and monetary policies worldwide make currencies a bad investment and commodities a good one, says investment icon Jim Rogers.

"All governments around the world are debasing their currencies," he says. "There may come a time when we all have to have all of our money in real assets."

While Rogers owns gold himself, he notes that the precious metal has soared since the beginning of 2009 — to the tune of 26 percent. "Anything that goes up that far, that fast should consolidate and rest," he told CNBC.

"I like to buy what's cheapest. Silver is cheaper than gold, on a historical basis; natural gas is cheaper than oil."

With speculators rushing into oil and gold, now’s a good time for investors to stay on the sidelines, Rogers says.

As for the currency market, Rogers anticipates the Chinese currency, known as the yuan or renminbi, will soar in coming years along with China’s economic strength.

"I expect the renminbi to double, triple, quadruple over the next few decades," he said.

"Just as the Japanese yen . . . went up 400 percent over the past few decades against the dollar, the renminbi will too."

The short term trend for the currency is less certain. Chinese officials appear to be in conflict over whether to let the renminbi appreciate.

The central bank appeared to recently signal that the currency would soon rise. But other officials said afterward that China won’t be bossed around by the United States.