Image: Jewelry store © Baerbel Schmidt, Getty Images

While many on Main Street are struggling, companies that sell to the biggest spenders -- among them Tiffany (TIF), Cartier, LVMH Moët Hennessy Louis Vuitton (LVMUY) and Rémy Cointreau (REMYF) -- are having themselves a merry little Christmas.

Luxury-goods sales are surging here and abroad. Profits are widening. And stocks are flying high.

Last summer (with impeccably bad timing), fund manager Guggenheim/Claymore wound up the Claymore/Robb Report Global Luxury Index exchange-traded fund, which tracked a broad basket of the world's top luxury stocks.

With the help of company filings and data from FactSet, I've reconstructed it. And if the fund were still around, it would be zooming.

"The luxury sector was the sector to be in in 2010," says Caroline Reyl, who manages a 1 billion-euro-plus, luxury-focused premium-brands fund for Pictet, an asset management company in Zurich. "Our fund is up 44% this year. We're slightly above our peak from 2007."

What are the reasons? Some of this is a stock market effect, she says. Luxury stocks have been playing catch-up since plummeting during the crash.

But the really interesting story relates to the fundamentals. Luxury-goods companies are selling to the two groups of people who have any money left: the rich, who are getting richer and richer, and consumers in emerging markets, who are getting richer.

"About 40% of the sales of premium brand companies are related to the emerging-market consumer," says Reyl. Cargo ships are carrying a lot of Swiss watches, cases of champagne and fancy Italian shoes to the newly wealthy in China, Brazil and India. And emerging-market tourists are carrying a lot of luxury goods home themselves when they travel.

Greater China -- including Hong Kong and Taiwan -- accounts for 15% of global luxury demand, says Reyl. She believes that by the end of 2011 China will have overtaken Japan, once the powerhouse of luxury sales.

Luxury companies that slashed costs during the recession, weeding out waste and closing down weak stores, are seeing the results flow through to their bottom lines.

It's not just about emerging markets, either. High-end consumers here in the United States are in much better shape than those further down the economic ladder, and they're spending again.

Sales at Tiffany's flagship New York City store are up 8%. Luxury giant LVMH -- which has more than 500 U.S. stores, and whose brands include Fendi, Givenchy and Donna Karan, as well as Louis Vuitton itself -- says U.S. sales have jumped 15% this year. The Swiss watch federation says exports of Swiss watches to the United States are up nearly 15% through November.

And the blue blood's ultimate blue chip, Compagnie Financière Richemont (CFRUY), which owns Cartier, Van Cleef & Arpels, Montblanc and a whole host of other brands, says strong U.S. sales helped drive total revenue growth across the Americas this year by an impressive 37% in the six months to September.

Consultancy Bain's latest global survey on the luxury goods industry estimates that U.S. luxury sales will grow 12% this year -- including a remarkable 22% gain for fancy shoes and other branded leather goods.

By contrast, total retail sales across the entire U.S. economy have risen by a more modest 6% or so this year.

Who's buying? Hardly the middle class. With unemployment high, home prices slumping and the economy sluggish, too many are either struggling or watching their pennies.

But the elite have money. And they are starting to spend again.

The rich and the very rich have seen a sharp rebound in their fortunes following the crash, according to the most recent wealth report from consultancy Capgemini.

Pictet's Reyl notes that the luxury retailers seeing the biggest gains are often those at the top of the tree. We're not talking about "mass affluent" retailers like Saks (SKS) or Neiman Marcus, but the kind like those run by Richemont and LVMH.

Have luxury stocks risen too far? They're far from cheap. Reyl says that after the gains of the past year, stocks in the industry are now, on average, about 19 times forecast earnings.

Most value investors would steer clear. But these companies enjoy astonishingly fat margins and buoyant cash flow. (Tiffany makes 58 cents of gross margin for each dollar spent there.) Many have strong customer loyalty and economic moats. I'd rather be in the business of selling $500 handbags than buying them. Especially if the rich continue to get richer.

And of course, these are growth plays. If you're looking for bets on emerging-market consumers, they are cheaper than many sky-high emerging-market stocks themselves. Reyl notes that consumer companies in China frequently trade for 30 times forecast earnings.

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It's always dangerous to jump on a bandwagon, but the underlying themes are exceptionally strong. Emerging-market consumers are getting richer and embracing luxury brands with gusto.

The brave may dip in their toes today. The more cautious may want to add these luxury goods companies to a watch list, in case the markets have a sale any time soon. The best luxury brands never go on sale -- but their stocks, fortunately, often do.