A grading report measures four things: how much the stone weighs, how colorless it is, how clean it is under magnification, and, only if the stone is round, how well it is cut. That is the entire list. Almost everything that decides whether a diamond looks beautiful on a hand is either absent from the page or not graded at all, and that is exactly as true for lab-grown stones as for natural ones.
Three things matter most, and the report is quiet about all three. Transparency: some diamonds are crisp and some are faintly milky, and a milky stone with excellent grades still looks dull, like a window that needs cleaning. Where the flaw sits: a mark tucked under a prong is invisible for life, while the same mark under the middle of the stone catches your eye every day, and both carry the same clarity grade. And cut on any shape that isn't round: ovals, cushions, emeralds and pears get no cut grade whatsoever, even though cut is the single biggest reason one stone looks brighter than another.
Reading those things is the job, and it is why I hold the GIA Applied Jewelry Professional credential on top of thirty years of buying. The training is in assessing a stone by eye rather than reading its paperwork. It is also the answer to the question I get most often: why does this particular stone online look like such a bargain? Usually it isn't one. A diamond priced well below what its grades suggest is priced that way because something is visibly wrong with it that the report does not record.
