The International Olive Council requires its members to taste from dark blue containers that prevent them from seeing the tonality of the liquid. However, in a sample tasting it is useful to consider the color and appearance of the extra virgin olive oil. For both types of tasting, it is recommended that the cup is covered with the hand to heat the oil. The color can vary from emerald green to golden yellow, with a wide range of shades in between. Colors outside of that range are considered defective.