Ice, ice, baby.

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Ever wonder why some of your cocktails come with one big ice cube and others brimming with crushed ice? It’s not just for looks. Ice is the one ingredient in your cocktail with a specific job. Rather, two specific jobs: chilling and dilution.

Meltwater (melted water from the surface of the ice) is what makes drinks cold. The ice in the drink is there to keep the cocktail cold, not make it cold. But most drinks want to be diluted, for different reasons and at different stages. A properly made martini is stirred with cubes of ice until it’s chilled and just slightly diluted—exactly 50 turns of your spoon. Boozier numbers like mint juleps and tiki drinks often come filled with crushed ice or ice pellets. These small shapes melt more quickly to help dilute a sweet and potent cocktail (and help you sip more slowly).

The larger the ice the slower it melts, so choose large cubes for drinks that you want cold, but not too diluted. Think: a negroni or a couple of fingers worth of scotch. Standard-sized ice cubes, about 1-inch square, should generally be used in cocktails that are stirred and strained, like Manhattans and martinis. If you want to use them in the drink itself, just make sure you've properly shaken or stirred.

A quick word on shaking versus stirring: a shaken cocktail will get colder faster than a stirred one, since it’s exposed to more of the ice's surface area as it’s jostled around inside the shaker. It also results in a frothier, cloudier cocktail—not something you’re always after. Tiny shards of ice can also slip through the strainer into your glass. Stirring offers a slower dilution and a crystal clear drink, and ultimately more control. Both are acceptable, depending on your preferences.

Cracked ice, whether cracked in your palm with the back of a spoon or chipped off a block with a pick, is best for shaken drinks. All that surface area cools down your margarita fast without diluting it too much, so it’s super cold when it gets strained over fresh ice.

What ice should you use at home? It depends on what cocktail you're making. Cubes are a safe bet, and silicone molds mimic the pristine Kold-draft ice used in many of the finest cocktail programs. If you want to play around with the big boys, trays for larger cubes are widely available, too. Skip the ice spears, which end up knocking into your teeth. Spherical molds are cool, but you can get the same effect by freezing water in a balloon. Tie the balloon to the rack in your freezer so it doesn’t get a flat bottom. When you’re ready to build your drink, run the ice ball under cold water until it melts just enough to fit inside your rocks glass. Spheres will melt the slowest because they have less surface area than a cube (remember geometry? Or was that trigonometry?). So use those beautiful orbs for the slow sippers.

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A few final tips: ice absorbs and gives off flavors, so it’s best to avoid the stuff that comes out of your fridge door (tastes like plastic). Instead, freeze in trays and transfer to a resealable plastic bag as soon as the ice is frozen.

Using distilled or filtered water will further prevent any funky flavors from creeping into your drink as the ice melts. A little fussy maybe, but if you really want to amp up your custom cocktail program, that’s the way to go.

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