We're perfectly happy eating in a Chinese restaurant. But will we start banking in a Chinese bank?

It's not as crazy as it sounds. As The Wall Street Journal's Lingling Wei reported Wednesday, the Bank of China here in the U.S. has started allowing American customers to open an account and to invest up to $4,000 per day—and a total of $20,000 a year—in Chinese yuan, or renminbi. Until now, you had few options to hold money in yuan, which is a "closed" currency managed, and protected, by Beijing.

The bank has three U.S. branches—two in New York, and one in Los Angeles. You'll have to fill out paperwork to open an account and provide two forms of ID. And there's a minimum deposit of $500.

Is this a good idea? You may wonder why anyone would do this. Investing in Chinese currency may sound like something best left to speculators.

But in reality this may be no more exotic than, say, Peking duck. Holding some of your money in Chinese currency—as part of a diversified portfolio, as they say—might be a very sensible move for all of us.