I chose a lab-grown diamond to have set in my fiancée's engagement ring. It looks stunning, is significantly larger than I would have been able to afford if sticking to "natural" stones, and nobody can tell the difference. It's certified by IGI, which most people will tell you is not a good thing (you would generally look for GIA certification, and GIA refuse to certify lab-grown diamonds), but if you find a stone that is graded highly across the board by an IGI lab (colour D or E, cut Ideal or Excellent and clarity >VS1) it seems unlikely you'll be disappointed once it's set in a ring.