Question about price stats

[reds]

When looking at chart for 2-2.99 oval cuts under si2 for example the 3a and 3b average cost is higher than the 2b. Is that correct? If so why? Thank you.

 

[pricescope]

Price stats merely show average prices for diamonds listed today. Since there is no generally accepted fancy cut grading system there might be diamonds of higher AGA grade listed for less.