Deterioration marks: These are the areas inside antique jades and having shapes like the legs of the ant or cow’s hair. Therefore, deterioration marking sometimes is called aging spots, ant’s leg or cow’s hair. This phenomenon of physical or chemical transformation of jade substances may be caused by underground heat, pressure and chemicals through time. Some sources claimed that the length of time to cause these deterioration marks are at least one thousand years. If it is true, this fact may be served as an important criterion to date the age of antique jade.