For me, there needs to be a balance. I don't expect to receive a flawless, ideally cut, perfectly colorless diamond engagement ring that's also a decent size. I'm willing to sacrafice a little quality for size.
Nobody is walking around with a loupe looking at my ring. And there have actually been market studies that take into account both the average observer and those who consider themselves "experts" -- virtually no difference between the eye of the casual "experts" and casual observer. I really don't think anybody is going to be MORE critical of my diamond than *I* myself will be.
I agree with this. Unfortunately for me, my SO will be choosing the diamond although I get to choose my setting. It will be a surprise and I am hoping for no bigger than a 1.5c center stone within the top 3 levels of each "C" category