I've said it before, and I'll say it again: I think there's just something so chic and effortless about a wedding stack that doesn't sit totally flush. In my opinion, a gap between your engagement ring and wedding band gives your stack character and makes it truly one of a kind - no mistaking your set for something from a big box store! Your fabulous great aunt or your chic French best friend aren't spending their time worrying about how their diamonds fit together, so why should you feel obligated to?
Now, if you don't like the look of ring gap, by all means, please do get the set you want - there are so many elegant ways to style a flush fit stack too! I just mean to free you from the external expectation that your set "should" look a certain way.
Ring gap looks best with a low set engagement ring that has a lot of finger coverage. Split shanks, side stones and tapered shoulders are all great examples of ring styles that minimize the negative space between the rings. A large center stone or a large face on the ring, particularly with a stone shape that isn't elongated, can do the trick as well. Here are a few examples of Hera rings stacked together with gap so you can get inspired!
Victor Pear + Laurel band (L); Sabine Emerald Cut + Prague band (R)
Audrey Round + Athens band (L); Daisy Emerald Cut + Hepburn band (R)
Audrey Old Mine Cut + Yara band (L); Theo Round + Athens band (R)
Victor Round + Twist band (L); Margot + Hepburn band (R)