Ice plays a very important role in the Japanese bartending world. The hand-carved ice balls that you might have seen in whiskey bars around the globe is a Japanese invention that not only gives a stylish look to the drink but also it keeps the beverage cold and less diluted than regular ice cubes.
Science explains the trick: the spherical shape has a smaller surface area, which makes the ice balls melt slower than cubes. It means that a spherical shaped ice will provide more time to savour a glass of whiskey on the rocks, before it gets watery. A crucial point for carving an ice ball is choosing a block of clear ice without any cloudiness or cracks. Once this block is cut into smaller chunks, skillful bartenders are able to carve one ice ball in less than three minutes.