(WSJ) - As the market for fine wine grows, so does the opportunity for making money from passing off a cheap blend as pricey aged Bordeaux.

Wine counterfeiters "are getting really sophisticated," says Charles Curtis, a New York-based wine consultant who, through his company Wine Alpha, offers a service that checks for fakes in the cellars of wealthy collectors throughout the world. "People are reusing old bottles, reapplying labels and corks—it's complex."

Few wine collectors have seen as many old bottles as Mr. Curtis, a former head of wine for Christie's auction house in Asia and the Americas. He now advises private clients on how to start or sell a collection as well as verifying the wines they own.

The problem of fakes is particularly acute in Asia, where the market for fine wine has boomed thanks to the rise of a new wealthy class amid strong economic growth in the region in recent years. Hong Kong now rivals New York and London as the world's most active center for wine auctions.

"They're acquiring faster than they're drinking or selling in Asia, whereas they're acquiring less in the West," he said, adding that because of the shift of demand eastward, the fakes often end up there, too. China, where many like to show off the expensive label rather than savor the drink inside, has become a major destination for fakes.