Tiffany (NYSE:TIF), Ralph Lauren (NYSE:RL) and Coach (NYSE:COH) all registered great performances in the first half of 2011. But with the U.S. economy growing at less than 1% and 14 million people out of work, how could that be?

A quick look at these luxury goods purveyors reveals that things are going great. Wealthy Americans aren’t the only ones willing to spend — the rich around the world are gladly grabbing up these iconic brands.

Just take a look at Tiffany. Its value has tripled since 2009, and now that it has ended a joint venture with Swiss watch retailer Swatch, Tiffany could be a takeover target. Since June 2009, Tiffany’s value has grown from about $3 billion to $8.6 billion, and it’s expected to enjoy 30% revenue growth in the next few years as it continues to expand in Asia and Europe. Third Asset Management, a New York money manager, estimates that Tiffany could be sold for as much as $12 billion as it enjoys a growing share of China’s emerging affluent.

Meanwhile, Ralph Lauren also is enjoying strong growth in Europe and Asia. One analyst expects Ralph Lauren to get 60% of its growth from these markets in the future. By spending $500 million in capital expenditures for its expansion in these markets, Ralph Lauren will get a bigger share of the high-rent consumers in these areas, and if it can keep its prices up, it will enjoy a bottom-line boost, partially on a 50% drop in cotton prices.

Coach’s leather handbags are enjoying a spurt in global demand. In the past 12 months, its sales have grown 15% on 20% net income growth — yielding fantastic 21% profit margins. Coach seems to be enjoying not only growth in China and other East Asian markets, but also improved sales and profits in the U.S. As CEO Lew Frankfort pointed out after Coach reported its fiscal 2011 results in early August, North American revenues were up 17% thanks to market share gains, higher productivity and distribution expansion. Finally, Coach is benefiting from new men’s products and its digital strategies.

These consumer goods companies are attracting newly affluent consumers around the world who are willing to pay a price premium for what they perceive as prestigious American brands. Tapping that hunger for the accoutrements of success is boosting their growth, but does this mean all three companies are good investments? Here’s a quick breakdown of the three luxury retailers:

• Coach: Very profitable company, somewhat overpriced stock. Coach revenues are up 15.3% in the past year, but it earns a whopping 21.2% net profit margin. And its price/earnings-to-growth ratio is a slightly overvalued 1.27 (a PEG ratio of 1.0 is considered fairly valued) on a P/E of 19.3 on earnings forecast to grow 15.2% to $3.90 in fiscal 2013.
• Tiffany: Profitable company, expensive stock. Tiffany revenues are up 14% in the past year, and it earns a solid 11.9% net profit margin. And its PEG ratio is an expensive 1.53 on a P/E of 21.4 on earnings forecast to grow 13.9% to $4.28 in fiscal 2013.
• Ralph Lauren: Profitable company, expensive stock. Ralph Lauren revenues are up 13.7% in the last year, and it earns an impressive 10.5% net profit margin. Yet its PEG is a high 1.51 on a P/E of 22.3 on earnings forecast to grow 14.8% to $7.82 in fiscal 2013.

None of these luxury leaders is a cheap stock. But of the three, Coach — with its rapid growth and wide profit margins — is best-positioned if it exceeds revenue expectations in the future.

Peter Cohan has no financial interest in the securities mentioned.