As we head into earnings season in the United States, you may be tempted to focus all of your attention on domestic stocks. Avoid that temptation.

While the S&P 500 certainly capped off an impressive week of gains last week, the bulls are really starting to run overseas. So if you are interested in a little diversification, you should consider investing in Spain, Turkey and South Africa.

Let's take a look at the iShares exchange-traded funds (ETFs) that track stocks in each of these countries: the MSCI Spain Index Fund (EWP), the MSCI Turkey Investable Market Index Fund (TUR) and the MSCI South Africa Index Fund (EZA).

Last week, when the SPDR S&P 500 ETF (SPY) was up 5.06% on the best one-week performance for the S&P 500 in a year, the Spain fund, the Turkey fund and the South Africa fund were up 12.24%, 7.38% and 7.03%, respectively.

"When most people think of Africa, images of business and commerce don't usually spring to mind -- more like wildlife, safaris and famine," suggests Nathan Slaughter.

In The ETF Authority, he explains, "But those perceptions are beginning to change as these countries continue to industrialize. And at the vanguard of this transformation is South Africa." Here, he looks at the iShares MSCI South Africa ETF (NYSE: EZA).

Slaughter explains, "Once a backwater country shunned by most of the international community, South Africa has made great strides over the past decade and continues to evolve. Fifteen years ago the government began an aggressive overhaul of South Africa's economy.

Carlton Delfeld reveals his latest global ETF picks and warns of leveraged funds.

Q. Carlton, in your last newsletter, you commented on the low valuations of several global markets, including Ireland, Singapore, UK, and Sweden, among others. Have you since added any ETFs from these regions to your portfolios?

A. Yes, I have added iShares MSCI South Africa Index (NYSEArca: EZA), iShares MSCI Singapore Index (NYSEArca: EWS), and the iShares MSCI United Kingdom (NYSEArca: EWU). South Africa is in part a currency and commodity play. The United Kingdom is very much predicated on global financial recovery, and Singapore will likely be a core holding.

Q. Each of these regions seems to have its own stress points right now. Do you think that South Africa is particularly vulnerable to a global slowdown? Hasn't Singapore been hit hard by the bear market in China? And isn't the UK just moving into a housing decline that may rival that of the US?

A. South Africa, China and the UK are all trading at attractive valuations. They all have challenges. The South Africa Rand has been a strong currency and will come back with higher gold prices, the UK is already moving through the housing issue and its financial-oriented market has already been hammered. Lastly, Singapore is a very high-quality China play.