Do you know different color of clay bars in a same grade?
yes, different color in same grade of clay bar.
For Example, Same purple color of clay bar in different grade;
MARFLO China, purple clay bar for fine, grade, heavy and King system...

Marflo Mexico, purple clay bar in medium
In 2012, purple if the year color. many company like to do the purple color. 
3M  claybar,  Japan  Clay Bar,  etc....  they  are  also  use the purple color