Grading of Japanese green tea powder

I knew Japanese Green teas are graded by Extra, Choicest, Choice, good
medium, Medium Dust etc. etc....

But today I have heard from a Japanese guy that- in Japan there are 3 grades
of Green tea powder:-

1.Highest Grade
2.Standard Grade
3.Cosmetic Grade

he couldn't elaborate more then this but he showed quiet strong confidence
about his knowledge on this matter. Any idea guys? Something really new to
me.

Ripon
(From Bangladesh)