CLEAR & COOL: Superpremium vodkas are ideal in an up martini.

Born from water, air, earth and fire, no purer representation of time and place exists than the quintessential eau-de-vie, vodka. Its transparency and brilliant character are an intriguing combination, two reasons why vodka continues to be the best-selling category of spirits in the U.S. It accounts for over 25% of all distilled spirits sold in the country, eclipsed only by the combined sales figures for all whiskies亡cotch, Irish, Bourbon and Canadian. All major indicators suggest the current bull market for vodka shows no signs of abating.

Despite their transparency, all top-shelf vodkas are not created equal. Where they're distilled usually speaks volumes about style and technique. How the vodka is distilled and from what—e.g., potatoes, rye, corn or wheat—is significant.

Surprisingly, what likely has the greatest effect on the finished vodka is its water source. Water provides the spirit with its genetic marker and contributes to aroma, taste and mouth-feel.

One of the factors propelling the vodka category is the steady flow of new brands crossing our borders, most professing legacy and asingular twist. This procession of new arrivals, both imported and American, has helped fuel consumer interest. To assist you in telling one contender from another, here's a scouting report on the latest field of entries.

• Boru Vodka: Made by West Cork Distillers, County Cork, Ireland, Boru is quadruple-distilled in small batches from grain and soft spring water and filtered through 10 feet of Atlantic Irish oak charcoal.
• Ciroc Snap Frost Vodka: This is the first and only vodka made entirely from grapes. The "snap frost" Mauzac grapes are picked late in the season, allowing them to attain higher sugar content. Ciroc is distilled five times in traditional copper pot stills.
• Domaine Charbay Dry/Clear Vodka: Made at the family-owned distillery in Ukiah, CA, Dry/Clear Vodka is microdistilled from Midwestern grain and spring water.
• Hangar One Vodka: Long known for eauxdevie and alembic brandies, St. George Spirits in Alameda, CA, is becoming better known for Hangar 1 Straight Vodka, a small batch, potdistilled grain vodka.
• Ikon Premium Vodka: Produced 1,500 kilometers from Moscow, Ikon Premium Vodka is a continuous-distilled vodka made from grain and artesian water, which is then filtered four times through Russian birch charcoal.
• Jean-Marc OX Vodka: This small batch alembic spirit is distilled nine times from four varieties of French wheat and limestone-filtered spring water. Because it is entirely handmade, only 200 bottles of the super-premium vodka can be producedper hour.
• Jewel of Russia: Crafted in the traditional Russian style, from a blend of rye, hardy winter wheat and artesian spring water, this vodka is distilled in continuous stills, then repeatedly filtered through high-absorption screens.
• Level by Absolut: Produced in Sweden, Level is 100% wheat vodka made by both continuous and small-batch distillation. Blending the two types of vodka creates a light, clean result with texture and a broad taste profile.
• Magadanskaya Vodka: The super-premium Russian vodka has been made for more than 100 years in the once-closed Siberian city of Magadan. This historic spirit is made from grain, potatoes and pure mineral water from the Tal'skaya Springs.
• Shakers Vodka: The first ultrapremium American vodka, Shakers is distilled entirely from the heart of Minnesota-wheat. The wheat is fermented in spring water, distilled in a six-column still and meticulously filtered.
• Stolichnaya Elit Vodka: The first ultraluxury vodka available in the U.S., small-batch Elit is double-distilled from purified glacier water and select winter wheat. It's "freeze-filtered," a technique first employed in the days of the czars.
• Xellent Vodka: A smallbatch artisan product made in Switzerland from high-grade rye and glacier water. The handmade, limited-production vodka is crafted to exacting standards, which is evident in every facet of its personality.
• Zyr Vodka: Made near Moscow, ultrapremium Zyr is distilled five times from premium rye, winter wheat and spring water. The vodka is rigorously filtered for purity through a proprietary system of filters, one of which is birch tree charcoal.