Of all the world’s wines, one of the riskiest to make is ice wine, produced from grapes left on the vine long after harvest. The grapes are picked when they are covered in ice and the juice within has frozen — that is, if severe weather hasn’t already destroyed them. When pressed, each grape gives only droplets of juice while the proportion of its natural sugar, which remains unfrozen, has doubled. The result is a distinctive wine of such concentrated flavors and nectarean sweetness that they are usually sold only in half-bottles.

Few places have the weather conditions that can produce authentic ice wine, and the outstanding ones are Germany, Austria, Canada and the Finger Lakes region of New York state.

A fine example from Germany is the Riesling Eiswein 2004 ($40) made by the 200-year-old winery, Valckenberg in the Rheinhessen. An elegant, goldshaded wine of great depth, its aroma evokes apple and honey and has a racy acidity that perfectly balances the wine’s sweetness.

From Austria’s Burgenland region, there is Steindorfer Eiswein Cuvée Klaus 2004 ($39), a wine brimming with fruit flavors and a rich, almost syrupy texture. Add to that a long, lingering finish.

The Finger Lakes region in northern New York state is a natural home for ice wine, and Hunt Country Vineyards makes a lovely one from Vidal Blanc ($45), a French-American hybrid grape. Harvested when the temperature is 10 degrees Fahrenheit, the grape creates a wine that is luscious with a bouquet of floral scents and a basket of pear and sweet citrus aromas.

Peller Estates in the Niagara Peninsula of Canada also has an ideal climate for ice wine, which it produces from several grape varieties. Its Riesling Icewine 2006 ($91) is deep gold, bright, satiny and ambrosial — a full-bodied wine with vivid fruit flavors, especially of ripe apricots with peaches and sweet citrus fruits in the background.

These are authentic ice wines. There are also wineries that produce “ice wines,” without the right climate, without risk. They pick the grapes at harvest, put them in a cold storage warehouse and turn down the thermostat. They can control everything but the final result — the beautiful, succulent richness and taste that only nature can provide.