It depends on a number of factors. For instance, will there be only one stone or will there be many? Pavé style bands and halos can also add carats to an engagement ring, even if a focal stone is modest in size.
Don’t forget that the cut of a stone can factor into weight and also perceived size. A well-cut high-quality stone in an ideal setting can make a ring look larger and more impressive. This is where working with an expert custom jeweler can save you money while giving you an engagement ring that leaves a big impression, no matter the number of carats.