Dr Kris, you do know that Rio Tinto mined Merlin for around 4...

Dr Kris, you do know that Rio Tinto mined Merlin for around 4 years (about 0.5 million cts), including the current pipes.
It produced predominantly white and brown stones with a few large Fancy Yellows, I don't believe there were any other significant coloured stones. Large white stones are far more likely than significant greens and blues (a single 0.12ct blue stone is not significant!). The colour within a diamond pipe tends not to change with depth.