Simplify the following text for a Grade 10 native English-speaking person.
Original: ISO 3632 deals exclusively with saffron and establishes four empirical color intensity grades : IV ( poorest ) , III , II , and I ( finest quality ) .
Simplified: Namely , ISO 3632 deals exclusively with saffron . It establishes four empirical grades of color intensity : IV ( poorest ) , III , II , and I ( finest quality ) .