What is a AAA black diamond?

Apparently, there is a jewelry grading system that includes five grades, including 'superfine', 'AAA', 'AA' and 'commercial'. This is the definition of a triple-A grade:

"AAA:-(SI1 - SI2) Or Big Bargain

This grade denotes that the product in question is clean, well cut & polished, lively color but poses variation in color consistency."