A 3 piece suit is a beautiful phenomenon but you can definitely wear your suit vest without the jacket. The question, though, is that if you do, should your vest have lapels?
Take a look at the following vest: Sean John Pinstriped Vest:
This vest doesn’t have lapels but the following vest does:
The truth of the matter is that if your jacket has lapels, your vest doesn’t need to. If you are wearing the vest as a standalone, it could have lapels and it could also not – does not make too much of a difference. The lapels add a layer of formality and ornament to your attire. We do feel, though that wearing lapels with your vest, when you are also wearing your suit jacket, has the potential of looking slightly overdone – and it may take some attention away from your killer tie, but we are also not denying the possibility of this being done correctly (the picture above shoes how this is done properly).