The whole minimum solutio dilution, maximum cooling line of reasoning smelled like bullshit to me. And efficiency doesn't have meaning until you explain what input and outcome you are measuring. Chipped ice in a shaker will coola drink faster -- more surface area. And a big sphere will cool it slower. If I have two identical drinks in identical glasses at the same temperature, and from the same freezer put a one ounce sphere in one and one ounce of chipped ice in the other I expect the chipped ice drink to reach freezing before the other. But i would expect the dilution when the drink reached freezing to be the same for each, since cooling should be proportional to the amount ice melted. If the ice chips melted (and diluted) much faster it's probably because it is doinga better job of keeping the drink and the glass evenly and thoroughly cold. If cold and undiluted is really that important, keep a bottle and a heavy mug in the deep freezer like grandma did, or try drinking faster. ------------------------------ Making clear pretty ice cubes is about reducing internal stress that causes cracks. Freezing slower helps. Wrapping an ice cube tray in a couple dish towels is enough to make noticably clearer cubes. Not $6.50 clear, but noticable.Glace Ice claims that the design of their cubes — which come in cube or sphere shapes — provide minimum dilution, maximum cooling, and should be enjoyed with "premium spirits."
The sphere is "the most efficient shape in nature" and "the most mathematically efficient way to cool your drink," according to the company's website.