[OJFord]

Maybe a specialist could tell a natural, formed over thousands of years, flaw from a lab-grown flaw, but really I think it's more like you can get a better grade from a lab (and especially with consistency, frequency, at a much lower price due to being rare to find naturally occurring). i.e. you can get flawed and coloured lab-grown diamonds too. (A mix of taking less care/time, older equipment, and binning the results like silicon wafers I assume.)