Quality of saffron is studied on the basis of specialized laboratory measuring and is classified through the study of properties including Chrosine (color agent), Picrochrosine (agent of  bitterness and taste of saffron) and Safranol (agent of aroma and odor of saffron), other factors which effects the quality of saffron are the remaining of saffron flavor and some of the outer non-organic compounds (ash of saffron).The world standards under No. 3632 is compiled for the classification and grading of saffron by ISO International Organization. This standard merely discussing and studying the saffron on specialized basis.On the basis of this standard, 4 grades  and types are determined considering the color power of saffron. The weakest is known as saffron of grade 4 and by increasing color power is classified into  grades 1, 2 and 3 with the finest and most powerful color-blending. (The Iranian saffron and Tak saffron are classified as the finest quality saffron by ISO.