Color and clarity of the stone
Ice made from boiled water, when frozen, will have a clear color, usually transparent and smooth. That's because the boiled water has had air bubbles and some impurities removed during the boiling process. If you use boiled water twice to make ice, the finished product you will get is clear, not cloudy ice.
Ice made from unboiled water is often milky white because it still contains many impurities. Although impurities dissolved in water cannot be seen, when frozen, they accumulate, making the ice cubes cloudy.
โImpurityโ does not always mean germs or bacteria. Anything other than water present in the water can be considered an impurity. Unboiled water contains a lot of impurities, but most of them are not harmful to us. In fact, some of them (calcium and magnesium, for example) are actually beneficial for your health. Various impurities also give water its characteristic taste.